Source: https://patents.google.com/patent/JP5493532B2/en
Timestamp: 2020-08-08 22:26:47
Document Index: 498039357

Matched Legal Cases: ['art 101', 'art 103', 'art 3', 'art, 6', 'art, 22', 'art, 23', 'art, 24', 'art, 31', 'art, 32', 'art, 33']

JP5493532B2 - Load driving device and electric vehicle using the same - Google Patents
Load driving device and electric vehicle using the same Download PDF
JP5493532B2
JP5493532B2 JP2009168836A JP2009168836A JP5493532B2 JP 5493532 B2 JP5493532 B2 JP 5493532B2 JP 2009168836 A JP2009168836 A JP 2009168836A JP 2009168836 A JP2009168836 A JP 2009168836A JP 5493532 B2 JP5493532 B2 JP 5493532B2
JP2009168836A
JP2011024370A (en
2009-07-17 Application filed by 富士電機株式会社 filed Critical 富士電機株式会社
2009-07-17 Priority to JP2009168836A priority Critical patent/JP5493532B2/en
2011-02-03 Publication of JP2011024370A publication Critical patent/JP2011024370A/en
2014-05-14 Publication of JP5493532B2 publication Critical patent/JP5493532B2/en
The present invention relates to a load driving device that can be applied to, for example, an electric vehicle that drives an electric motor with at least electric power supplied from a battery, and an electric vehicle using the load driving device.
As a load driving device represented by an electric vehicle, for example, a battery that generates a predetermined DC voltage, and a bidirectional type that boosts the DC voltage generated by the battery and obtains a power source for driving an electric motor based on the boosted voltage. 2. Description of the Related Art An electric motor control device is known that includes a step-up chopper unit and an electrolytic capacitor that is connected between the bidirectional type step-up chopper unit and an inverter unit for driving the electric motor and smoothes the DC voltage of the bidirectional step-up chopper unit. (For example, see Patent Document 1).
There is also known a variable voltage system that boosts a battery voltage by a boost converter and supplies the boosted voltage to a main capacitor and variably controls a system voltage output from the boost converter in accordance with an operating state of the motor (for example, non-voltage Patent Document 1).
That is, in the motor system, motor loss (copper loss + iron loss), inverter loss (on loss + switching loss), boost IGBT loss (on loss + switching loss), boost reactor loss (copper loss + iron loss), etc. Loss occurs and the condition for minimizing this system loss is that the system voltage be approximately the same as the induced voltage of the motor. Since this induced voltage changes depending on the motor operating state (rotation speed, torque), the loss can be minimized by variably controlling the system voltage in accordance with the motor operating state.
As shown in FIG. 15, the configuration of the conventional example described in Patent Document 1 boosts the battery voltage of the battery 100 by a bidirectional boost chopper unit 101 configured by a DC-DC conversion circuit, and this bidirectional boost. The structure which connected the electrolytic capacitor 102 between the positive electrode side line Lp and the negative electrode side line Ln used as the output side of the chopper part 101, and also connected the inverter part 103 as a DC-AC conversion circuit in parallel with this electrolytic capacitor 102 Have Then, the three-phase alternating current output from the inverter unit 103 is supplied to the electric motor 104.
Here, the bidirectional step-up chopper unit 101 is interposed between the IGBT 1 and IGBT 2 connected in series between the positive electrode side line Lp and the negative electrode side line Ln, and the connection point between the IGBT 1 and IGBT 2 and the positive electrode side of the battery 100. It is comprised with the inserted reactor L. FIG.
Further, the battery 100 constitutes a high-voltage DC power supply by connecting several units of 1 unit / several V in series.
In general, the rotational speed of the motor 104 and the DC voltage Ed across the electrolytic capacitor 102 are controlled to have a relationship as shown in FIG. That is, when the rotation speed of the motor 104 is from zero to a predetermined rotation speed N 0 , the DC voltage Ed is made equal to the battery voltage Vb, and the rotation of the motor 104 is controlled by PWM control of each switching element constituting the inverter unit 103. Control the number. And, between the rotational speed of the electric motor 104 to a large predetermined number N 1 than a predetermined rotational speed N 0 exceeds a predetermined rotational speed N 0, increase in the rotational speed from 1 in the step-up ratio of the battery voltage Vb by the boost chopper 101 The rotational speed of the electric motor is controlled by gradually increasing the direct current voltage Ed from the battery voltage Vb and performing PWM control on each switching element of the inverter unit 103.
When the DC voltage Ed exceeds the predetermined rotation speed N 1 reaching the maximum value Ed MAX , the DC voltage Ed is fixed to the maximum value Ed MAX , and for further increase of the rotation speed of the electric motor 104, the inverter unit 103 is driven by one pulse from PWM control. Transition to control, field weakening control, etc. are executed.
JP 2001-275367 A
TOYTA Technical Review Vol.54 No.1 Aug. 2005, pages 42-51
However, in each of the above conventional examples, since the lowest DC input voltage value input to the inverter unit 103 serving as a DC-AC conversion circuit is the battery voltage value Vb, when the motor 104 is operated at a low speed, the inverter The unit 103 performs PWM control based on the battery voltage value Vb. As a result, the switching loss of the switching elements (IGBT and diode) increases, and the ripple of the flowing current also increases on the motor 104 side, so that the harmonic loss due to the carrier frequency component increases and the efficiency of the load driving device and the motor decreases. There is an unsolved problem of inviting.
Further, when the motor 104 is operated at a high speed, the battery voltage Vb is boosted by the boost chopper unit 101 as a DC-DC conversion circuit. In this case, in the case of the circuit of FIG. 16, since the IGBTs 1 and 2 and the diodes D1 and D2 operate, there is an unsolved problem that these semiconductor chips need to have appropriate capacitances.
Further, usually, an electric vehicle is mounted on a vehicle as a battery of several hundred volts by connecting a battery of several volts in a unit of several tens in series. However, if any one unit fails for some reason, the entire battery 100 becomes unusable because each battery unit is connected in series. Therefore, in the battery system simply connected in series as shown in FIG. 15, there is an unsolved problem that the reliability can be improved.
Therefore, the present invention has been made paying attention to the unsolved problems of the above conventional example, and even when a failure occurs in a part of the battery while improving the efficiency of the load driving device and the electric motor, It aims at providing the load drive device which can ensure normal operation, and an electric vehicle using the same.
In order to achieve the above object, a load driving apparatus according to an aspect of the present invention is a load driving apparatus that drives an AC motor using a DC power supply, and is provided on each of a positive electrode side and a negative electrode side of the DC power supply. A DC-DC converter having a positive electrode line and a negative electrode line connected via a positive electrode side switch circuit and a negative electrode side switch circuit, and at least two switching elements connected in series between the positive electrode line and the negative electrode line; A smoothing circuit having a smoothing capacitor connected in parallel with the DC-DC converter between the positive electrode side line and the negative electrode side line; and DC- that converts the DC power of the smoothing circuit into AC power and supplies it to the motor An AC converter, and the DC-DC converter connects an intermediate potential of the DC power source and a connection point between the switching elements through an intermediate potential line, Possess one configuration interposed reactor to between the potential line positive electrode side line and the negative side line, wherein the positive electrode side switching circuit and the negative switch circuit interposed in the positive electrode line and a negative line, the DC-DC Control for controlling on / off of the two switching elements of the converter, and selectively supplying at least the voltage of the DC power source and the voltage boosted by the DC-DC converter to the DC-AC converter parts that have a.
Further, in the load driving device according to another aspect of the present invention, the control unit controls one of the positive side switch circuit and the negative side switch circuit to be always in an off state and the other to be always in an on state, supplying a 1/2 voltage to the smoothing circuit are have a low power supply unit.
Further, in the load driving device according to another aspect of the present invention, the control unit controls both the positive-side switch circuit and the negative-side switch circuit to be always on, so that the voltage of the DC power source is supplied to the smoothing circuit. and it has a power supply unit in supplying.
Further, in the load driving device according to another aspect of the present invention, the control unit controls one of the positive side switch circuit and the negative side switch circuit to be always in an off state, and controls the other to be in a constantly on state, and the DC a switching element -DC converter unit with on-off control, which have a large power supply unit for supplying a voltage boosted in the reactor in the smoothing circuit.
Further, in the load driving device according to another aspect of the present invention, the control unit controls the positive switch circuit to an on state and controls the negative switch circuit to an off state; The second control mode in which the positive switch circuit is controlled to be turned off and the negative switch circuit is controlled to be turned on is alternately repeated in a time series.
The load driving device according to another aspect of the present invention is abnormal among the positive switch circuit and the negative switch circuit when one power supply unit sandwiching the intermediate potential of the DC power supply becomes abnormal. The switch circuit connected to the power supply unit is controlled to be always off, the switch circuit connected to the normal power supply unit is controlled to be always on, and the switch is connected to the normal power supply unit of the DC-DC converter. The switching element connected via the circuit is on / off controlled to supply DC power to the smoothing circuit.
Moreover, the electric vehicle which concerns on the other form of this invention is equipped with one of each said load drive device as an electric motor drive device which drives the drive wheel of a vehicle.
According to the present invention, the load drive device and the electric motor can be operated with high efficiency, and the normal operation of the electric motor can be ensured even when a failure occurs in a part of the DC power supply. .
Moreover, an electric vehicle having high reliability can be provided by applying the load driving device having the above effects to the electric motor driving device of the electric vehicle.
It is a block diagram which shows one Embodiment at the time of applying this invention to an electric vehicle. 1 is a circuit diagram showing a configuration example of a bidirectional switch circuit that can be applied to a first embodiment. It is a block diagram including the control part of embodiment of this invention. It is a characteristic diagram which shows the relationship between a motor rotational speed and the DC voltage of a smoothing circuit. It is a block diagram explaining the operation state in the case of driving an electric motor in a low-speed rotation area. It is a block diagram explaining the operation state in the case of driving an electric motor in a medium speed rotation area. It is a block diagram explaining the operation state in the case of driving an electric motor in a high-speed rotation area. It is a block diagram which shows other embodiment at the time of driving an electric motor in a high speed rotation area | region. It is a block diagram which shows other embodiment in the case of driving an electric motor in a high speed rotation area | region. FIG. 4 is a block diagram for explaining an operation state when one of the battery units of the DC power supply fails, where (a) shows a case where the battery unit BUb has failed and (b) shows a case where the battery unit BUa has failed. It is a block diagram which shows the structure of the control part in the case of driving an electric motor control apparatus in a low speed area | region, a medium speed area | region, and a high speed area | region. It is a block diagram which shows the control apparatus which considered the failure of the battery unit. It is a block diagram which shows the specific structure of the control part of the control apparatus of FIG. It is a block diagram which shows the modification of FIG. It is a block diagram which shows the conventional electric motor drive device. It is a characteristic diagram which shows the relationship between the motor rotational speed of a prior art example, and the DC voltage of a smoothing circuit.
FIG. 1 is a block diagram showing a load machine drive device according to a first embodiment of the present invention. In the figure, 1 is an electric motor drive device as a load drive device applied to an electric vehicle. The electric motor drive device 1 includes a DC power source 2 constituted by a battery, and a DC-DC connected in parallel to a positive electrode side line Lp and a negative electrode side line Ln derived from the positive electrode side and the negative electrode side of the DC power source 2, respectively. A conversion unit 3, a smoothing circuit 4, and a DC-AC conversion unit 5 are provided. Then, AC power output from the DC-AC converter 5 is supplied to the AC motor 6. The drive torque generated by the AC motor 6 is transmitted to the drive wheels 9 via the speed reduction mechanism 7 and the differential gear 8 as necessary.
The DC power source 2 is configured so that a unit can obtain a battery voltage Vb of several hundred volts by connecting batteries of several volts in series of several tens. The batteries connected in series are divided into two to constitute battery units BUa and BUb. A positive electrode side line Lp is derived from the positive electrode side of the battery unit BUa via the positive electrode side switch circuit SWp, and a negative electrode side line Ln is derived from the negative electrode side of the battery unit BUb via the negative electrode side switch circuit SWn. Further, an intermediate potential line Lm is derived from a connection point between the battery units BUa and BUb, that is, an intermediate potential point Pm. Here, the positive electrode side switch circuit SWp and the negative electrode side switch circuit SWn are obtained by connecting in parallel a semiconductor switch element having a reverse breakdown voltage such as a mechanical switch such as a contactor, a thyristor, or an insulated gate bipolar transistor (IGBT). Can be configured. For example, as shown in FIG. 2 (a), a configuration in which IGBTTa and IGBTb having reverse breakdown voltage are connected in reverse parallel is applied, or as shown in FIG. 2 (b), IGBTc and IGBTd having no reverse breakdown voltage. Are preferably connected in series, and diodes Dc and Dd are connected in antiparallel to each IGBTc and IGBTd.
The DC-DC converter 3 has a configuration of a bidirectional step-up chopper circuit, and a switching element Q3a formed of a pair of IGBTs connected in series between the positive electrode side line Lp and the intermediate potential line Lm. And Q3b. An intermediate potential line Lm of the DC power source 2 is connected to a connection point between the switching elements Q3a and Q3b via a reactor L. Diodes D3a and D3b are connected in antiparallel to the switching elements Q3a and Q3b, respectively.
Furthermore, the smoothing circuit 4 includes a smoothing capacitor C connected between the positive electrode side line Lp and the negative electrode side line Ln. The smoothing capacitor C smoothes the DC power output from the DC-DC converter 3. Turn into. The DC voltage Ed across the smoothing capacitor C is supplied to the DC-AC converter 5.
Furthermore, the DC-AC converter 5 has a configuration of an inverter circuit, and includes three switching arms SA21 to SA23 connected in parallel between the positive electrode side line Lp and the negative electrode side line Ln. Each of the switching arms SA21 to SA23 includes switching elements Qja and Qjb (j is 21 to 23) configured by, for example, IGBTs connected in series between the positive electrode side line Lp and the negative electrode side line Ln, and the switching elements Qja. And diodes Dja and Djb connected in antiparallel to Qjb. The connection points of the switching elements Qja and Qjb are AC output points Pu, Pv, and Pw, and are connected to, for example, the star-connected coils Lu, Lv, and Lw of the AC motor 6 as a load.
The on / off control of the positive side switch circuit SWp and the negative side switch circuit SWn, and the PWM (pulse width modulation) of the switching elements Q3a and Q3b of the DC-DC converter 3 and the switching elements Q21a to 23b of the DC-AC converter 5 are described. The control is performed by the control unit 12 of the control device 11 as shown in FIG. Here, the speed command (or frequency command) Nm * of the AC motor 6 is input to the control unit 12.
Now, the vehicle travels at a low speed (for example, about 0 to 20 km / h) at the time of traffic jam, and the AC motor 6 has a rotational speed Nm of the AC motor 6 equal to or lower than a predetermined rotational speed N 01 as shown in FIG. When the low-speed rotation driving is set, for example, as shown in FIG. 5A, the battery unit BUb is selected with, for example, the positive-side switch circuit SWp always turned off and the negative-side switch circuit SWn always turned on. To do. In this control state, the positive side of the battery unit BUb is connected to the positive side of the smoothing capacitor C of the smoothing circuit 4 via the reactor L via the diode D3a connected in antiparallel with the switching element Q3a, and the negative electrode of the battery unit BUb. The side is supplied to the negative side of the smoothing capacitor C of the smoothing circuit 4 via the negative side switch circuit SWn and the negative side line Ln. Therefore, since the battery unit BUb is a voltage Vb / 2 that is half of the battery voltage Vb, the voltage Vb / 2 is charged in the smoothing capacitor C. For this reason, the DC voltage Ed between the positive potential part Vp and the negative potential part Vn at both ends of the smoothing capacitor C is Vb / 2.
Since the DC voltage Ed (= Vb / 2) of the smoothing circuit 4 is supplied to the switching arms SA1 to SA3 of the DC-AC converter 5, the switching elements Q21a to Q23a and Q21b to the switching arms SA1 to SA3 are supplied. The AC motor 6 can be driven to rotate at a low speed by PWM control of Q23b by the control unit 12 with a duty ratio based on the speed command (or frequency command) Nm * . Therefore, the AC motor 6 is supplied with a voltage Vb / 2 that is half the battery voltage Vb to the DC-AC converter 5, and the switching elements Q21a to Q23a and Q21b to Q23b of the DC-AC converter 5 are PWM-controlled. Is done. Therefore, the switching loss of the DC-AC converter and the harmonic loss of the AC motor 6 can be reduced.
Similarly, as shown in FIG. 5B, the battery unit BUa is selected by always turning on the positive switch circuit SWp and turning off the negative switch circuit SWn. For this reason, the positive side of the battery unit BUa is connected to the positive side of the smoothing capacitor C of the smoothing circuit 4 via the positive side switch circuit SWp and the positive side line Lp. On the other hand, the negative electrode side of the battery unit BUa is connected to the negative electrode side of the smoothing capacitor C via the reactor L and the diode D3b and further via the negative electrode side line Ln. Therefore, as in FIG. 5A described above, the DC voltage Ed across the smoothing capacitor C becomes a voltage Vb / 2 that is half the battery voltage Vb, and this DC compression Ed (= Vb / 2) is DC -Supplied to the AC converter 5. Then, similarly to the above-described FIG. 5A, the switching elements Q21a to Q23a and Q21b to Q23b of the DC-AC conversion unit 5 are PWM-controlled so that the switching loss of the DC-AC conversion unit and the AC motor 6 Harmonic loss can be reduced.
Further, a mode in which the battery unit BUa shown in FIG. 5B is used in the low-speed rotation region in order to reduce the burden on one battery unit BUa (or BUb) in the low-speed rotation region of the AC motor 6. A and mode b using the battery unit BUb shown in FIG. 5A may be alternately switched in time series.
Next, the vehicle travels at a medium speed (about 20 km / h to 70 km / h), for example, so that the vehicle travels in an urban area, and the rotational speed Nm of the AC motor 6 exceeds the predetermined rotational speed N 01 in FIG. A description will be given of a case where the rotational drive is performed in a medium speed rotation region where the rotation speed is greater than N 01 and lower than N 0 .
In this medium speed rotation region, as shown in FIG. 6, both the positive electrode side switch circuit SWp and the negative electrode side switch circuit SWn are controlled to be always on to select the battery units BUa and BUb. In this control state, the smoothing capacitor C of the smoothing circuit 4 is charged with the battery voltage Vb obtained by adding the voltages of the battery units BUa and BUb. For this reason, the DC voltage Ed across the smoothing capacitor C becomes the battery voltage Vb, and a voltage twice that of the low-speed rotation driving state described above is supplied to the DC-AC converter 5. For this reason, the AC motor 6 can be rotationally driven at a high voltage by PWM-controlling the switching elements Q21a to Q23a and Q21b to Q23b of the DC-AC converter 5.
In a state where the AC motor 6 is driven to rotate at medium speed, the driving method is the same as that of the conventional example of FIG. 12 described above, but there is no circuit through the reactor L and the DC-DC converter 3 is PWMed. There is no driving. For this reason, while being able to prevent the copper loss and the iron loss in the reactor L, the switching loss and ON loss in the DC-DC conversion part 3 can be prevented.
Next, for example the vehicle is traveling at high speed running on an expressway (for example, 80 km / h or higher), the rotational speed Nm of AC motor 6 is greater than the predetermined rotational speed N 0 exceeds a predetermined rotational speed N 0 in FIG. 4 A case of rotationally driving in a high-speed rotation region where the rotation speed is N 1 or less will be described.
In this high-speed rotation region, as shown in FIG. 7, the battery unit BUb is selected by always turning on the positive switch circuit SWp and turning off the negative switch circuit SWn. Then, the positive side of the battery unit BUb is connected to the connection point of the switching elements Q3a and Q3b of the DC-DC converter 3 via the intermediate potential line Lm and the reactor L, and the negative side is connected to the negative side via the negative side switch circuit SWn. Connect to line Ln.
In this state, the switching element Q3B of the DC-DC converter 3 is PWM-controlled. At this time, when the rotational speed Nm of the AC motor 6 is the predetermined rotational speed N 0 , the duty ratio of the PWM signal supplied to the gate of the switching element Q3b is selected so that the step-up rate α is “2”. Thereby, the DC-DC converter 3 boosts the battery voltage Vb / 2 to the battery voltage Vb, and the smoothing capacitor C of the smoothing circuit 4 is charged with this boosted voltage. For this reason, the DC voltage Ed at both ends of the smoothing capacitor C is equal to the battery voltage Vb, and is equal to the DC voltage Ed in the medium speed rotation region described above.
In this step-up operation, a current flows through the reactor 7 when the switching element Q3a of the DC-DC converter 3 is always turned off and the switching element Q3b is turned on. From this state, by turning off the switching element Q3b, a counter electromotive voltage is generated in the reactor 7 so that a current continues to flow, and the counter electromotive voltage is charged to the smoothing capacitor C of the smoothing circuit 4 through the diode D3a. Is boosted.
Thereafter, by increasing the duty ratio of the PWM signal supplied to the switching element Q3b and gradually increasing the step-up rate α from “2”, the DC voltage output from the DC-DC converter 3 is made higher than the battery voltage Vb. gradually increasing, gradually increasing the rotational speed Nm of AC motor 6 from the predetermined rotational speed N 0.
Then, by increasing the step-up rate α, the DC voltage Ed of the smoothing capacitor C of the smoothing circuit 4 charged by the DC voltage output from the DC-DC converter 3 reaches a preset maximum voltage Ed MAX . Then, thereafter, the duty ratio of the PWM signal supplied to the gate of the switching element Q3b is fixed so that the output voltage of the DC-DC converter 3 is maintained at the maximum voltage Ed MAX set in the smoothing capacitor C.
When the AC motor 6 is rotationally driven in the high-speed rotation region, the circuit is equivalent to the above-described conventional example, but the battery voltage Vb serving as the input power supply is Vb / 2. For this reason, the burden on the switching element Q3b and the diode D3a at the time of boosting and the burden on the battery unit BUb for supplying power are increased compared to the conventional method.
As shown in FIG. 8, the increase in the load on the battery unit BUb is achieved by connecting the positive side switch circuit SWp and the negative side switch circuit SWn between the neutral potential line Lm and the intermediate potential point Pm between the battery units BUa and BUb. A similar intermediate potential switch circuit SWm is inserted, and a bypass switch circuit SWa is provided between a connection point of the battery unit BUa and the positive side switch circuit SWp and a connection point of the switch circuit SWm and the reactor L.
According to this configuration, when the AC motor 6 is rotationally driven in the high-speed rotation region, the positive side switch circuit SWp and the intermediate potential switch circuit SWm are always turned off, and the negative side switch circuit SWn and the bypass switch circuit SWa are always turned on. By selecting the battery units BUa and BUb as states, the voltage output from the DC power supply 2 is set as the battery voltage Vb.
In this case, when the rotational speed Nm of the AC motor 6 is a predetermined value N 0 with respect to the duty ratio of the PWM signal supplied to the gate of the switching element Q3b of the DC-DC converter 3, the step-up rate α is “1”. By setting so that, the DC voltage Ed across the smoothing capacitor C can be made equal to the battery voltage Vb when the rotational speed Nm of the AC motor 6 is a predetermined value N 0 .
As described above, according to the configuration of FIG. 8, since the battery voltage Vb can be supplied to the reactor L of the DC-DC converter 3, the burden on the battery units BUa and BUb at the time of the boosting operation is made equal. The load on the units BUa and BUb and the load on the switching element Q3b and the diode D3a of the DC-DC converter can be made equal to those in the conventional example shown in FIG.
Further, in order to reduce the burden on one battery unit BUb in the high-speed rotation region of the AC motor 6, a mode a in which the battery unit BUa shown in FIG. 9A is used in the high-speed rotation region, and FIG. The mode b using the battery unit BUb shown in FIG.
That is, in mode a, the positive side switch circuit SWp is always on, the negative side switch circuit SWn is always off, the battery unit BUa is selected, and the switching element Q3b of the DC-DC converter 3 is always off. The PWM signal having a duty ratio corresponding to the rotational speed Nm of the AC motor 6 is supplied to the gate of the switching element Q3a.
Thus, when the switching element Q3a is in the on state, a closed circuit is formed from the battery unit BUa to the negative electrode side of the battery unit BUa via the positive side switch circuit SWp, the switching element Q3a, and the reactor L. Current flows.
Thereafter, when switching element Q3a is turned off, a counter electromotive voltage is generated in reactor L so that a current continues to flow. At this time, the positive side of the battery unit BUa is connected to the positive side of the smoothing capacitor C via the positive switch side circuit SWp and the positive side line Lp, and the negative side of the smoothing capacitor C is connected to the negative side line Ln, the diode D3b, the reactor L, and The battery unit BUb is connected to the negative electrode side via the intermediate potential line Lm. For this reason, the counter electromotive voltage generated in the reactor L is added to the battery voltage Vb / 2 of the battery unit BUa, and the smoothing capacitor C of the smoothing circuit 4 is charged. For this reason, the DC voltage Ed at both ends of the smoothing capacitor C becomes a voltage obtained by boosting the battery voltage Vb / 2, and this DC voltage Ed is supplied to the DC-AC converter 5 so that the DC-AC converter 5 The switching elements Q21a to Q23a and Q21b to Q23b are PWM controlled to drive the AC motor at high speed.
In mode b, the boosting operation is the same as in FIG.
Then, by alternately operating the mode a and the mode b in time series, the burden on the battery units BUa and BUb can be equalized, and the switching elements Q3a and Q3b and the diode D3a in the DC-DC conversion unit 3 can be equalized. And the burden of D3b can also be equalized. As described above, since the burden on the switching elements Q3a and Q3b and the diodes D3a and D3b can be equalized, the temperature rise of the semiconductor chip can be suppressed, and the reliability of the semiconductor chip can be improved. .
Incidentally, even in the configuration of the conventional example shown in FIG. 15 described above, when the switching element IGBT2 constituting the bidirectional boost chopper unit 101 composed of the DC-DC converter circuit is turned on at the time of boosting, a current is supplied to the reactor L. When the switching element IGBT2 is inverted to the OFF state, a counter electromotive voltage is generated in the reactor L so that a current continues to flow, and this counter electromotive voltage is charged to the electrolytic capacitor 102 through the diode D1. For this reason, only the switching element IGBT2 and the diode D1 are in the operating state, and the burden is increased with respect to the switching element IGBT1 and the diode D2 in the non-operating state, and the burden on the semiconductor becomes uneven.
Further, when rotating the rotational speed Nm of AC motor 6 exceeds a predetermined rotational speed N 1, as in the conventional example described above, the switching element Q21a~Q23a and Q21b~Q23b the DC-AC converter 5 This is achieved by shifting from PWM control to one-pulse control or by performing field-weakening control.
Further, during the regenerative operation in which the vehicle is in a braking state or traveling downhill and the AC motor 6 operates as a generator, the generated power is supplied from the DC-AC converter 5 to the DC. -It is supplied to the DC converter 3 and is stepped down by the DC-DC converter 3 and supplied as a charging current to the battery units BUa and BUb.
In the first embodiment, when the AC motor 6 is driven in the medium speed rotation region, the DC voltage Eb across the smoothing capacitor C of the smoothing circuit 4 is supplied to the battery regardless of the rotation speed of the AC motor 6. The case where it is set equal to the voltage Vb has been described. However, the present invention is not limited to the above configuration, and the circuit configuration shown in FIG. 8 is applied so that the switch circuits SWp and SWa are always turned off and the switch circuits SWn and SWm are always turned on in the medium speed rotation region. Then, the battery unit BUb is selected, and the output voltage of the DC-DC converter 3 is gradually increased from Vb / 2. As a result, the DC voltage Ed across the smoothing capacitor C may be gradually increased from Vb / 2 as the rotational speed Nm increases as shown by the dotted line in FIG. At this time, when the rotational speed Nm reaches the predetermined rotational speed N 0 , the switch circuit SWm is always switched to the off state, and the switch circuit SWa is switched to the constantly on state to switch to the boosted state of the battery voltage Vb.
Further, when the battery unit BUb fails, as shown in FIG. 10A, the positive switch circuit SWp is always turned on and the negative switch circuit SWn is always turned off. It can be set as the structure similar to the mode a shown to 9 (a), and drive control of the AC motor 6 can be continued in a normal state.
Conversely, when the battery unit BUa fails, as shown in FIG. 10B, the positive switch circuit SWp is always turned off and the negative switch circuit SWn is always turned on, as described above. It can be set as the structure similar to the mode b shown in FIG.9 (b), and drive control of the AC motor 6 can be continued in a normal state.
Thus, even when one of the battery units BUa and BUb fails, the normal operation of the AC motor 6 can be continued, so that the reliability as an automobile can be improved.
As described above, in order to control the positive side switch circuit SWp, the negative side switch circuit SWn, the DC-DC converter 3 and the DC-AC converter 5 in accordance with the rotational speed region of the rotational speed Nm of the AC motor 6. The control unit 12 of the control device 11 is configured as shown in FIG.
That is, the control unit 12 includes a low-speed rotation region control unit 21, a medium-speed rotation region control unit 22, and a high-speed rotation region control unit 23, and these low-speed rotation region control unit 21, medium-speed rotation region control unit 22, and high-speed rotation region control. A selection unit 24 for selecting the unit 23 is provided.
Here, as shown in FIG. 5A or 5B, the low-speed rotation region control unit 21 performs on / off control of the positive switch circuit SWp and the negative switch circuit SWn, and the DC-DC conversion unit 3. The switching elements Q3a and Q3b are turned off, and the switching elements of the DC-AC converter 5 are PWM-controlled.
As shown in FIG. 6 described above, the medium-speed rotation region control unit 22 controls both the positive side switch circuit SWp and the negative side switch circuit SWn to be in an on state, and turns on the switching elements Q3a and Q3b of the DC-DC conversion unit 3. Both are controlled to be in an OFF state, and the switching element of the DC-AC converter 5 is PWM-controlled. Note that the medium-speed rotation region control unit 22 may perform on / off control of the switching circuits SWp, SWn, SWm, and SWa in the configuration of FIG.
As shown in FIG. 7, the high-speed rotation region control unit 23 controls one of the positive side switch circuit SWp and the negative side switch SWn to an on state, controls the other to an off state, and a DC-DC conversion unit. One of the three switching elements Q3a and Q3b is boosted by PWM control, and the switching element of the DC-AC converter 5 is PWM controlled. In the high-speed rotation region control unit 23, as shown in FIGS. 9A and 9B, the step-up control may alternately control the mode a and the mode b in time series.
The selection unit 24 includes a window comparator 27 having two comparators 25 and 26 to which the rotation speed command Nm * is input on the non-inverting input side. Predetermined rotational speeds N 01 and N 0 are individually input to the inverting input sides of the comparators 25 and 26.
Accordingly, the comparator 25 selects the speed command Nm * is the logical value "1" when when less than the predetermined rotational speed N 01 logic "0", the rotational speed command Nm * is the predetermined rotational speed N 01 higher The signal SL1 is output.
Further, the comparator 25 has a logical value “0” when the rotational speed command value Nm * is less than the predetermined rotational speed N 0 , and a logical value “1” when the rotational speed command Nm * is greater than or equal to the predetermined rotational speed N 0. The selection signal SL2 is output.
The selection signals SL1 and SL2 are supplied to an AND circuit 28 in which the input sides of both the selection signals SL1 and SL2 are inverted inputs, and an AND circuit 29 and an AND circuit 30 in which the input sides of the selection signals SL1 are inverted inputs. .
The output of the AND circuit 28 is supplied to the low-speed rotation region control unit 21, the output of the AND circuit 29 is supplied to the medium-speed rotation region control unit 22, and the output of the AND circuit 30 is supplied to the high-speed rotation region control unit 23. The low-speed rotation region control unit 21, the medium-speed rotation region control unit 22, and the high-speed rotation region control unit 23 are configured to be in an operating state when the AND output that is input is a logical value “1”.
Thus, the rotational speed command Nm * is when a predetermined rotational speed N 01 is less than the selection signal SL1 and SL2 output from the comparator 25 and 26 are both logic "0". For this reason, since only the AND circuit 28 outputs the logical value “1”, only the low-speed rotation region control unit 21 is in an operating state, and the AC motor 6 is driven to rotate at a low speed.
When the rotation speed command Nm * is equal to or higher than the predetermined rotation speed N 01 and lower than the predetermined rotation speed N 0 , the selection signal SL1 output from the comparator 25 becomes a logical value “1” and the selection output from the comparator 26 The signal SL2 becomes a logical value “0”. For this reason, since only the AND circuit 29 outputs the logical value “1”, only the medium speed rotation region control unit 22 is in the operating state, and the AC motor 6 is driven to rotate at the medium speed.
Further, when the rotational speed command Nm * is equal to or higher than the predetermined rotational speed N 0 , the selection signal SL1 output from the comparator 25 has a logical value “1”, and the selection signal SL2 output from the comparator 26 also has a logical value “1”. It becomes. For this reason, since only the AND circuit 30 outputs the logical value “1”, only the high-speed rotation region control unit 23 is in an operating state and drives the AC motor 6 to rotate at high speed.
Further, when the controller 12 of the control device 11 also considers the failure of the battery units UBa and UBb, as shown in FIG. 12, the failure is detected by detecting the respective terminal voltages Va and Vb of the battery units BUa and BUb. The battery failure detection units 31a and 31b for detecting the presence or absence of the battery failure are provided, and the battery failure detection signals BAa and BAb output when the battery failure detection units 31a and 31b detect the battery failure are supplied to the control unit 12. Then, in the control unit 12, as shown in FIG. 13, a unit BUb failure control unit 32 that performs control when the battery unit BUb fails, and a unit BUa failure control that performs control when the battery unit BUa fails. And a normal-time control unit 34 having the configuration shown in FIG. 11 that performs control when the battery units BUa and BUb are normal.
Here, the unit BUb failure control unit 32 selects the battery unit BUa with the positive switch circuit SWp always on and the negative switch circuit SWn always off as shown in FIG. In addition, the switching element Q3a of the DC-DC conversion unit 3 is PWM-controlled, and each switching element of the DC-AC conversion unit 5 is PWM-controlled.
Further, the unit BUa failure control unit 33 selects the battery unit BUb with the positive electrode side switch circuit SWp always in an off state and the negative electrode side switch circuit SWn in an always on state as shown in FIG. In addition, the switching element Q3b of the DC-DC converter 3 is PWM-controlled, and each switching element of the DC-AC converter 5 is PWM-controlled.
Then, the battery failure detection signals BAa and BAb are supplied to the selection switch circuit 35. When the battery failure detection signals BAa and BAb are both logical values “0”, the normal control unit 34 is selected and the switch circuits SWp, SWn are selected. The DC-DC converter 3 and the DC-AC converter 5 are controlled. On the other hand, when the battery failure detection signal BAa has a logical value “0” and the battery failure detection signal BAa has a logical value “1”, the selection switch circuit 35 selects the unit BUb failure control unit 32 and switches the switch circuits SWp and SWn. The DC-DC converter 3 and the DC-AC converter 5 are controlled. Further, when the battery failure detection signal BAa is a logical value “1” and the battery failure detection signal BAa is a logical value “0”, the unit BUa failure control unit 33 is selected by the selection switch circuit 35 and the switch circuits SWp, SWn. The DC-DC converter 3 and the DC-AC converter 5 are controlled.
In this way, by configuring the control unit 12 of the control device 11 as shown in FIGS. 12 and 13, when the battery units BUa and BUb of the DC power supply 2 are normal, the AC is changed according to the rotational speed command Nm *. When the rotational speed of the electric motor 6 is controlled and one of the battery units BUa and BUb fails, the normal rotational speed control of the AC motor 6 can be continued using a normal battery unit.
In the above embodiment, the case where the intermediate potential point Pm between the battery units BUa and BUb is connected via the reactor L between the switching elements Q3a and Q3b constituting the DC-DC converter 3 has been described. However, the present invention is not limited to the above configuration, and as shown in FIG. 14, the reactor La is divided into reactors La and Lb having a capacity that is half the capacity of the reactor L, and the reactor La is divided into the positive-side switch circuit SWp and the DC− The positive electrode line Lp between the collectors of the switching element Q3a of the DC conversion unit 3 is inserted, and the reactor Lb is inserted into the negative electrode side line Ln between the negative electrode side switch circuit SWn and the emitter of the switching element Q3b of the DC-DC conversion unit 3. You may make it do. Even in this case, the same effects as those of the above-described embodiment can be obtained.
Moreover, in the said embodiment, although the case where battery unit BUa and BUb were applied as DC power supply 2 was demonstrated, it is not limited to this, Two sets of fuel cell units, two sets of solar cell units, etc. Other DC power supply units can also be used. Further, the DC power supply 2 may be configured by connecting different units such as a battery unit, a fuel cell unit, and a solar cell unit.
Furthermore, in the above-described embodiment, the case where the IGBT is applied as the switching element has been described. However, the present invention is not limited to this, and a power MOSFET, a gate turn-off thyristor (GTO), a static induction transistor is used according to the power used. Any switching element such as (SIT) can be applied.
Furthermore, in the above-described embodiment, the case where the present invention is applied to an electric vehicle has been described. However, the present invention is not limited to this, and a load drive that drives an AC load other than an AC motor of the electric vehicle with a DC power source 2. The present invention can also be applied to an apparatus.
DESCRIPTION OF SYMBOLS 1 ... Electric motor drive device, 2 ... DC power supply, BUa, BUb ... Battery unit, SWp ... Positive electrode side switch circuit, SWn ... Negative electrode side switch circuit, Lp ... Positive electrode side line, Ln ... Negative electrode side line, Lm ... Intermediate potential line, DESCRIPTION OF SYMBOLS 3 ... DC-DC conversion part, L, La, Lb ... Reactor, 4 ... Smoothing circuit, C ... Smoothing capacitor, 5 ... DC-AC conversion part, 6 ... AC motor, 11 ... Control apparatus, 12 ... Control part, DESCRIPTION OF SYMBOLS 21 ... Low-speed rotation area | region control part, 22 ... Medium speed rotation area | region control part, 23 ... High-speed rotation area | region control part, 24 ... Selection part, 31a, 31b ... Battery failure detection part, 32 ... Unit BUb failure time control part, 33 ... Unit BUb failure control unit, 34... Normal control unit
A load driving device that drives an AC motor using a DC power source,
A positive line and a negative line connected to a positive side and a negative side of the DC power source via a positive side switch circuit and a negative side switch circuit, respectively;
A DC-DC converter having at least two switching elements connected in series between the positive electrode line and the negative electrode line;
A smoothing circuit having a smoothing capacitor connected in parallel with the DC-DC converter between the positive electrode side line and the negative electrode side line;
A DC-AC converter that converts the DC power of the smoothing circuit into AC power and supplies the motor to the motor,
The DC-DC conversion unit connects an intermediate potential of the DC power source and a connection point between the switching elements by an intermediate potential line, and a reactor is connected to one of the intermediate potential line and the positive electrode side line and the negative electrode side line. have a structure in which interposed,
Controlling ON / OFF of the positive side switch circuit and the negative side switch circuit interposed between the positive line and the negative line, and the two switching elements of the DC-DC converter, and at least the voltage of the DC power supply, A load driving device comprising a control unit that selectively supplies the voltage boosted by the DC-DC conversion unit to the DC-AC conversion unit .
The control unit controls one of the positive-side switch circuit and the negative-side switch circuit to be always in an off state and controls the other to be in a constantly on state, and supplies a ½ voltage of a DC power source to the smoothing circuit. load driving device according to claim 1, characterized in that to have a.
Wherein the control unit, wherein said controlling both the positive electrode side switching circuit and the negative switching circuit always on, characterized in that it have a power supply unit in supplying the voltage of the DC power supply to the smoothing circuit Item 2. The load driving device according to Item 1.
The control unit is configured such that one of the positive side switch circuit and the negative side switch circuit is always turned off, the other is always turned on, and the switching element of the DC-DC converter is turned on / off, load driving device according to claim 1, characterized in that to have a large power supply unit for supplying a voltage boosted in the reactor in the smoothing circuit.
The control unit controls the positive side switch circuit to an on state and controls the negative side switch circuit to an off state, and controls the positive side switch circuit to an off state, and controls the negative side The load driving device according to claim 2 or 4, wherein the second control mode for controlling the switch circuit to be in an on state is alternately repeated in a time series.
When one of the power supply units sandwiching the intermediate potential of the DC power supply becomes abnormal, the switch circuit connected to the abnormal power supply unit among the positive electrode side switch circuit and the negative electrode side switch circuit is controlled to be always off. In addition, the switch circuit connected to the normal power supply unit is controlled to be always on, and the switching element connected to the normal power supply unit of the DC-DC conversion unit via the switch circuit is controlled to be on / off. The load driving apparatus according to claim 1, wherein DC power is supplied to the smoothing circuit.
An electric vehicle comprising any one of the load driving devices according to claim 1 as an electric motor driving device for driving a driving wheel of a vehicle.
JP2009168836A 2009-07-17 2009-07-17 Load driving device and electric vehicle using the same Active JP5493532B2 (en)
JP2009168836A JP5493532B2 (en) 2009-07-17 2009-07-17 Load driving device and electric vehicle using the same
US12/838,414 US8297389B2 (en) 2009-07-17 2010-07-16 Load driving system and electric vehicle using the system
JP2011024370A JP2011024370A (en) 2011-02-03
JP5493532B2 true JP5493532B2 (en) 2014-05-14
ID=43464493
JP2009168836A Active JP5493532B2 (en) 2009-07-17 2009-07-17 Load driving device and electric vehicle using the same
US (1) US8297389B2 (en)
JP (1) JP5493532B2 (en)
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