JP4843938B2 - Power converter control method - Google Patents

Description

  The present invention relates to a method for controlling a power converter.

Japanese Laid-Open Patent Publication No. 2002-118981 (refer to Patent Document 1) discloses a configuration of driving a motor with high efficiency using a fuel cell as a main power source as a conventional technique. In this example, as shown in FIG. 1, the battery is connected in parallel with the fuel cell via the DCDC converter, and the output voltage of the DCDC converter is controlled to improve the output efficiency of the power source. . In addition, as a technique that eliminates the need for a DCDC converter, the inventors of the present application (in Japanese Patent Application No. 2004-200545) do not use a DCDC converter, and not only a combination of a fuel cell and a battery, but also a plurality of power sources. We are developing a power converter control method that can be used and distributed to reduce the overall volume and loss.
JP 2002-118981 A (paragraphs 0004-0005, FIG. 1)

  However, in the configuration of the first example, since the DCDC converter is used, the volume of the entire system including the power source, the power conversion device, and the motor is increased, and the DCDC converter is used for charging and discharging the battery. Loss occurs due to passing through. Therefore, the present invention provides a method of controlling a power converter that can reduce and reduce the overall volume and loss by using and distributing a plurality of power sources without using a DCDC converter, and not limited to a combination of a fuel cell and a battery. For the purpose.

  In the prior application (Application No. 2004-200545) listed below, in the embodiment, the semiconductor switch provided in the current path from the load such as a motor to the positive electrode of the power source is turned on / off. It is also possible to turn off the path to the power supply positive electrode. When both are turned off in this way, a voltage is generated at the terminal due to the differential value of the inductance and current of the motor, so that the semiconductor switch must use a voltage with which this voltage is also assumed. Therefore, an object of the present invention is to always secure a path from a motor to a DC power source by on / off control of a semiconductor switch, to suppress a voltage generated at a terminal, and to reduce the cost of the semiconductor switch.

In order to solve the above-described problems, a method for controlling a power conversion device according to the first invention includes:
The continuity from each of the plurality of DC power supplies to the multiphase AC motor is disconnected and the voltage pulses are generated and synthesized from the output voltages of the plurality of DC power supplies to generate a drive voltage to drive the multiphase AC motor. A control method for a power conversion device having, for each phase, a first switch group and a second switch group for connecting and disconnecting conduction from a load including the multiphase AC motor to each of the plurality of DC power sources ,
A path securing step in which at least one second switch group is always in a conductive state in each phase, and a current path from a load including the multiphase AC motor to at least one DC power source is secured in each phase;
It is characterized by including.

The control method of the power converter according to the second invention is
In the path securing step, the second switch is controlled based on at least one of a motor voltage command value of each phase or a command signal of a generated pulse .

Furthermore, the control method of the power converter according to the third invention is
The path securing step calculates a limit value of a voltage command value of each phase motor, and controls the second switch based on the limited voltage command value of each phase .

Furthermore, the control method of the power conversion device according to the fourth invention is:
The path securing step includes at least one of the second switch groups in each phase when the second switch group is all off for each phase based on all drive signals of the second switch group. Is turned on .

Furthermore, the control method of the power converter according to the fifth invention is:
A short-circuit prevention switch drive pulse generation step for generating a switch drive pulse command signal that prevents a short circuit of the inter-electrode paths having different potentials with respect to the first switch group and the second switch group in each phase;
A short-circuit permission switch drive pulse generating step for generating a switch drive pulse command signal that permits short-circuit between the same polarity for the second switch group in each phase, and
The path securing step outputs a switch drive pulse command signal that prevents the short circuit to the first switch group, and also allows a switch drive pulse that permits the second switch group to be short-circuited between the same polarities. And a signal output step of selecting and outputting the command signal .

Furthermore, the control method of the power conversion device according to the sixth invention is:
A short-circuit prevention switch drive pulse generation step for generating a switch drive pulse command signal that prevents a short circuit of the inter-electrode paths having different potentials with respect to the first switch group and the second switch group in each phase;
A determination step of determining that the second switch group is all off for each phase from all of the switch drive pulse command signals that prevent the short circuit with respect to the second switch group, and
The path securing step is a switch operation that turns on at least one of the second switch groups in each phase when it is determined in the determining step that the second switch group is all off for each phase. Including steps ,
It is characterized by that.

Furthermore, the control method of the power conversion device according to the seventh invention is:
The route securing step includes
Based on the magnitude comparison of the voltage values of the plurality of DC power supplies, the second switch provided in the path from the load including the multiphase AC motor to the DC power supply having a large voltage is made conductive .
It is characterized by that.

Furthermore, the control method of the power converter according to the eighth invention is:
Two DC power supplies are provided, and the negative electrode of the first DC power supply and the negative electrode of the second DC power supply of the two DC power supplies are connected, and pulses are generated and synthesized from the output voltages of these DC power supplies. A control method for a power conversion device that generates a drive voltage to drive an AC motor,
In the path of conduction from the positive electrode of the first DC power source to a second DC power supply positive electrode, a switch between the output terminals of the power converter to the positive pole of the first DC power source, an output terminal of said power converter And a first short-circuit prevention time generating step of switching any of the switch sets from OFF to ON after a predetermined time when both of the switches between the switch and the positive electrode of the second DC power supply are turned off. ,
In the path of conduction from the positive electrode of the first DC power source to a second DC power supply positive electrode, a switch between the output terminals of the power converter to the positive pole of the first DC power source, an output terminal of said power converter A first path securing time generation step of switching any one of the switch sets from on to off after a predetermined time when both of the switches between the switch and the positive electrode of the second DC power source are on. ,
In the path of conduction from the positive electrode of the second DC power supply to the first DC power supply positive electrode, a switch between the output terminal of the second positive electrode and the power converter of a DC power source, an output terminal of said power converter A second short-circuit prevention time generating step of switching any of the switch sets from OFF to ON after a predetermined time when both sets of switches between the positive electrode of the first DC power supply and the switch are turned off;
In the path of conduction from the positive electrode of the second DC power supply to the first DC power supply positive electrode, a switch between the output terminal of the positive electrode and the power conversion device of the second DC power source, an output terminal of said power converter A second path securing time generation step of switching any of the switch sets from on to off after a predetermined time when both of the switch sets between the positive electrode of the first DC power source and the first set have passed.
When the positive potential of the first DC power supply is greater than the positive potential of the second DC power supply, control is performed so that the pulse generation by the first short-circuit prevention time generation step and the second path securing step is selected and output. When the positive potential of the first DC power supply is smaller than the positive potential of the second DC power supply, the pulse generation by the first path securing time generation step and the second short-circuit prevention time generation step is selected and output. A signal output step for controlling
The on-pulse of the switch between the output terminal of the power converter and the negative electrode is output from the power converter using the result of pulse generation by the first short-circuit prevention time generation step and the second short-circuit prevention time generation step. A switch between the terminal and the positive electrode of the second DC power supply and a switch between the output terminal of the power converter and the positive electrode of the first DC power supply are controlled to be generated when both are on. Control steps;
It is characterized by including.

Furthermore, the control method of the power converter according to the ninth aspect of the invention is
The signal output step includes
When comparing the magnitudes of the voltage values of the plurality of DC power supplies, a threshold value capable of performing hysteresis control is used.
It is characterized by that.

Furthermore, the control method of the power conversion device according to the tenth invention is
The motor voltage command value for each phase is a modulation rate command value in which the voltage command value is standardized by the power supply voltage, and the short-circuit prevention time of each switch, the voltage value of each AC power supply, and the power ratio of each AC power supply Based on the above, find the limit value of the motor voltage command value for each phase.
It is characterized by that.

Furthermore, the control method of the power converter according to the eleventh invention is
Either one of the two DC power supplies that can be regenerated is connected, and the negative electrode of the first DC power supply and the negative electrode of the second DC power supply are connected to each other from the output voltage of each of these power supplies. A method for controlling a power converter that generates a drive voltage of a motor by generating and synthesizing a pulse,
The switch drive signal conducting from the output terminal of the power converter to the first positive electrode, the switch drive signal conducting from the power converter output terminal to the second positive electrode, and the switch drive signal are both off. A step of outputting, for each phase, a drive signal for turning on a switch connected to a positive electrode of a regenerative power supply when the drive signal is
It is characterized by including.

As described above, the solving means of the present invention has been described as a method. However, the present invention can also be realized as a device, a program, and a storage medium recording the program, and the scope of the present invention. It should be understood that these are also included.
For example, when the first invention is realized as a device, the control device for the power conversion device according to the present invention provides:
A control device for a power converter that is connected to a plurality of DC power supplies, generates a drive voltage by generating and synthesizing pulses from respective output voltages of these DC power supplies, and drives an AC motor,
Route securing means for securing, in each phase, a current path from the load including the AC motor to at least one DC power source using at least one of the motor voltage command value of each phase or the generated pulse command signal. circuit),
It is characterized by including.

In addition, when the fifth aspect of the invention is realized as a device, the control device for the power converter is
A control device for a power converter that is connected to a plurality of DC power supplies, generates a drive voltage by generating and synthesizing pulses from respective output voltages of these DC power supplies, and drives an AC motor,
A short-circuit prevention pulse generation means (circuit) for generating a pulse command signal that prevents a short circuit between paths between different potentials;
A short-circuit permission pulse generating means (circuit) for generating a pulse command signal permitting a short-circuit between the same polarity;
Either a pulse command signal that prevents the short circuit or a pulse command signal that permits a short circuit between poles of the same polarity so as to secure a current path from the load including the AC motor to at least one DC power source in each phase. Signal output means (circuit) for selecting and outputting,
It is characterized by including.

  According to the first invention, the control signal of the motor voltage command value and the pulse command signal is used to generate a signal that secures a path that flows from the load in the direction of the DC power supply, secures a current path, and generates the signal at the terminal. By suppressing the voltage and using a circuit element with a low withstand voltage, the cost of the power conversion device can be reduced.

Further, according to the third invention, by restricting the motor voltage command value of each phase, it is possible to secure a path flowing from the load of each phase toward the DC power source. According to the fourth invention, on the basis of the drive signal of the switch of the power converter, at least one of the switches provided in the path flowing from the load toward the DC power source is turned on. Can be secured.

According to the fifth aspect of the present invention, when generating the pulse command signal, the signal in consideration of the short circuit prevention and the signal permitting the short circuit between the poles of the same polarity are generated. Recognizing a short circuit between poles of the same polarity can increase the opening time of the path that flows from the load to the DC power supply, and it is possible to secure a path that flows from the load to the DC power supply in each phase. . By selecting and outputting the case of preventing the short circuit between the same polarities and the case of permitting, it is possible to prevent the loss of the circuit element due to the short circuit current and to secure the current path.

Furthermore, according to the sixth aspect of the invention, when generating the pulse command signal, the short-circuit prevention and the current path are ensured, the output result of the command signal is judged, and the load is directed from the load to the DC power source. By providing means for turning on at least one of the switches provided in the flow path, a current path can be secured even in a state where the generation of the pulse command signal does not operate.

Furthermore, according to the seventh invention, by determining the magnitude of the power supply voltage, and selecting and outputting a signal considering short circuit prevention and a signal allowing the short circuit between the same polarity poles, It is possible to prevent loss of circuit elements and to secure a current path. In addition, according to the seventh aspect, the power supply voltage is determined, and when a short circuit between poles of the same polarity is permitted, a signal on a path through which an excessive short circuit current does not flow is selected and output. It is possible to prevent loss of circuit elements due to current and to secure a current path.

  Furthermore, according to the eighth invention, when generating a pulse of each switch of the power conversion device, a signal having a time for preventing a short circuit of the same polarity and a signal having a time for permitting a short circuit of the same polarity are provided. By generating and selecting and outputting these signals by comparing the power supply voltages, loss of circuit elements due to a short-circuit current can be prevented and a current path can be secured. According to the ninth aspect of the present invention, by providing hysteresis in the voltage magnitude comparison, frequent switching of comparison discrimination due to noise superimposed on the voltage signal detected by the voltage sensor can be prevented, and the switch can be switched on and off. Loss can be reduced.

Furthermore, a current path is secured by limiting the motor voltage command value for each phase , and the output result of the command signal is determined, and the switch provided on the path flowing from the load to the DC power supply By providing means for turning on at least one, a current path can be secured.

Furthermore, according to the tenth invention, even if these values change by obtaining the limit value from the ratio of the modulation factor command value, dead time, power supply voltage and power, the motor voltage of each phase The command value can be limited and a current path can be secured. According to the twelfth aspect of the present invention, by turning on the switch of the current path to the regenerative power source based on the drive signal of each switch, the current path can be changed without an unnecessary voltage increase of the smoothing capacitor. Can be secured.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 2 is a block diagram showing an example of a basic configuration of a power conversion device to which the control method according to the present invention is applied. As shown in the figure, a plurality of DC power sources 1 are connected to a load 3 including a motor and the like via a power converter 2. The power converter 2 generates a voltage from each output voltage of the DC power source 1 including a plurality of power sources and synthesizes a pulse to generate a drive voltage of an AC motor that is one of the loads 3 (power conversion 2a and a determination means 2b for determining that the switches are all off for each phase based on all drive signals of the switches on the current path from the load 3 including the AC motor to each DC power source. And ensuring a current path for each phase from the load including the AC motor to at least one DC power source using at least one of the motor voltage command value of each phase or the generated pulse command signal Means 2c are provided.
Further, the power conversion device 2 includes limit value calculation means 2d for obtaining a limit value of the motor voltage command value for each phase, and voltage limit means 2e for restricting the motor voltage command value for each phase to the limit value. Furthermore, the power converter 2 includes a short-circuit prevention pulse generating means 2f that generates a pulse command signal that prevents a short circuit between paths having different potentials, and a short circuit permission that generates a pulse command signal that permits a short circuit between the same polarity. The pulse generation signal 2g and the pulse command signal for preventing the short circuit and the short circuit between the same polarities are permitted so as to secure a current path from the load including the AC motor to at least one DC power source in each phase. There is provided signal output means 2h for selecting and outputting one of the pulse command signals.

  A first embodiment will be described. FIG. 4 shows a circuit diagram of the power conversion device according to the present invention. The negative electrode of the power supply 10a and the negative electrode of the power supply 10b are connected to the common negative electrode bus 15. A pair of semiconductor switches 107a, 108a, 109a and diodes 107b, 108b, 109b is connected between the common negative electrode bus 15 and each phase terminal of the motor 20 in the same manner as a generally known lower arm of an inverter. . The positive electrode bus 14 of the power supply 10a and each phase terminal of the motor 20 are connected by semiconductor switches 101a / 101b, 102a / 102b, 103a / 103b, respectively, capable of controlling bidirectional conduction. Further, semiconductor switches 104a / 104b, 105a / 105b, and 106a / 106b that can control bidirectional conduction are also connected between the positive electrode bus 16 of the power supply 10b and each phase terminal of the motor 20. A smoothing capacitor 12 is provided between the positive electrode bus 14 and the common negative electrode bus 15 of the power source 10a, and a smoothing capacitor 13 is also provided between the positive electrode bus 16 and the common negative electrode bus 15 of the power source 10b.

  The power converter 30 is a DC-AC power converter that generates a voltage to be applied to the motor based on the above three potentials, the common negative electrode bus, the positive electrode bus of the power source 10a, and the positive electrode bus of the power source 10b. The semiconductor switch provided in each phase of U phase (30U), V phase (30V), and W phase (30W) is a switch means that generates a voltage to be output to each phase of the AC motor. Alternatively, the necessary voltage is supplied to the motor by changing the ratio of the connection time.

  The configuration of the control unit 40 of the power conversion device will be described with reference to FIG. Reference numeral 41 denotes torque control means for calculating a d-axis current command value id * and a q-axis current command value iq * of the AC motor from a torque command given from the outside and the rotational speed of the motor. Reference numeral 42 denotes current control means for calculating voltage command values vd * and vq * for matching the dq-axis current command values id * and iq * and the dq-axis current values id and iq. id and iq are obtained from the three-phase currents iu and iv by the three-phase / dq conversion means 48. Reference numeral 43 denotes dq / 3-phase voltage conversion means for converting the dq-axis voltage command values vd * and vq * into three-phase voltage commands vu *, vv * and vw *. 44 is a U-phase voltage command generated from the voltage of each power supply according to the distribution target value (rto_pa, rto_pb) of the power Pa supplied from the power supply 10a and the power Pb supplied from the power supply 10b. vu_a *, vu_b *, V-phase voltage commands vv_a *, vv_b *, W-phase voltage commands vw_a *, vw_b * are voltage distribution means (hereinafter, a voltage command generated from the power supply 10a is referred to as a power supply 10a voltage command) The voltage command generated from the power supply 10b is referred to as a power supply 10b divided voltage command). 45, the voltage Vdc_a of the power source 10a and the voltage Vdc_b of the power source 10b are input, and the instantaneous modulation rate command mu_a *, which is a standardized voltage command, vu_a *, vu_b *, vv_a *, vv_b *, vw_a *, vw_b *, Modulation rate calculation means for generating mu_b *, mv_a *, mv_b *, mw_a *, mw_b *. Reference numeral 46 denotes a modulation rate correction unit that performs processing before performing PWM on the instantaneous modulation rate command and generates final instantaneous modulation rate commands mu_a_c *, mu_b_c *, mv_a_c *, mv_b_c *, mw_a_c *, mw_b_c *. 47 is PWM pulse generation means for generating a PWM pulse for turning on / off each switch of the power converter 30 based on the final instantaneous modulation rate command.

In FIG. 3, the voltage distribution means 44 and the standardized voltage command generation means 45 generate a voltage command value for setting the power distribution to a desired value. A voltage command vu *, vv *, vw * and a distributed power command value rto_pa (= 1−rto_pb) are input to the voltage distribution unit 44. From these, the power supply 10a divided voltage command and the power supply 10b divided voltage command are obtained by the following calculation.
vu_a * = rto_pa ・ vu *
vu_b * = rto_pb ・ vu *
vv_a * = rto_pa ・ vv *
vv_b * = rto_pb ・ vv *
vw_a * = rto_pa ・ vw *
vw_b * = rto_pb ・ vu *

Hereinafter, the modulation factor calculation unit 45, the modulation factor correction unit 46, and the PWM pulse generation unit 47 will be described in detail with reference to FIGS. FIG. 6 is a flowchart showing the calculation performed by each means of FIG. FIG. 7 shows a PWM pulse generation method. The following description is performed only for the U phase, but the same operation is performed for the V phase and the W phase.
Modulation rate calculation means 45
The modulation factor calculation means 45 performs calculation 2 shown in FIG. By normalizing the U-phase power supply 10a voltage command vu_a * and power supply 10b voltage command vu_b * with half the value of each DC voltage, the power supply 10a instantaneous modulation rate command mu_a * and the power supply 10b instantaneous modulation rate command Find mu_b *.
mu_a * = vu_a * / (Vdc_a / 2)
mu_b * = vu_b * / (Vdc_b / 2)

このように、電源10a分瞬時変調率指令ｍu_a*、電源10b分瞬時変調率指令ｍu*_bに分配電力目標値の大きさに応じた値を乗じるとともにオフセット値を減算することで、分配電力目標値の大きさが大きい電源から生成する電圧を大きくできるようにしている。 Modulation rate correction means 46
The modulation factor correction means 46 performs calculation 3 shown in FIG. In this calculation, the power supply voltage Vdc_a, Vdc_b and the distributed power target values rto_pa and rto_pb are used to correct the instantaneous modulation factor command mu_a * for the power supply 10a and the instantaneous modulation factor command mu * _b for the power supply 10b based on the following equations. Do.

In this way, the power supply 10a instantaneous modulation rate command mu_a * and the power supply 10b instantaneous modulation rate command mu * _b are multiplied by a value corresponding to the size of the distribution power target value and the offset value is subtracted to obtain the distribution power target. The voltage generated from the power supply having a large value can be increased.

PWM pulse generation means 47
In FIG. 7, a carrier for the power source 10a is a triangular wave carrier for generating PWM pulses for driving each switch in order to output a voltage pulse from the voltage Vdc_a of the power source 10a. Similarly, a triangular wave is used as the carrier for the power source 10b. Is provided. These two triangular wave carriers have an upper limit of +1 and a lower limit of −1, and have a phase difference of 180 degrees. Here, the signals for driving the U-phase switches are set as follows based on FIG.
A: Switch drive signal conducting from the power supply 10a to the output terminal B: Switch drive signal conducting from the output terminal to the negative electrode C: Switch drive signal conducting from the output terminal to the power supply 10a D: Power supply Switch drive signal conducting from 10b to output terminal E: Switch drive signal conducting from output terminal to power supply 10b

  First, a pulse generation method when a voltage pulse is output from the power supply 10a will be described. When outputting a PWM pulse from the power supply 10a, it is necessary to turn on A. When there is a potential difference between the positive electrode and the positive electrode and Vdc_a> Vdc_b, when both A and E are turned on, a current that short-circuits between the positive electrodes flows. For example, when A is switched from on to off at the same time and E is switched from off to on, it takes time for A to completely turn off. A short-circuit current flows, and the amount of heat generated by the semiconductor switch installed in this path increases. In order to prevent such an increase in heat generation, A and E are switched from OFF to ON after a time during which both the drive signals A and E are turned off. In this way, pulse generation is performed by adding a short-circuit prevention time (dead time) to the drive signal. Similar to adding dead time to the drive signals of A and E, dead time is added to E and C, and in order to prevent a short circuit between the positive and negative electrodes, dead to A and B and E and B. Add time.

A method for adding dead time to the A and E drive signals will be described below with reference to FIG.
In order to generate a drive signal with a dead time added, mu_a_c_up * and mu_a_c_down * offset from the mu_a_c * by the dead time are obtained as follows.
mu_a_c_up * = mu_a_c * + Hd
mu_a_c_down * = mu_a_c * − Hd
Here, Hd is obtained from the amplitude of the triangular wave (from the base to the apex) Htr, the period Ttr, and the dead time Td as follows.
Hd = 2Td · Htr / Ttr
The carrier and mu_a_c *, mu_a_c_up *, mu_a_c_down * are compared, and the drive signals for the A and E switches are obtained according to the following rules.
mu_a_c_down * ≧ If carrier for power supply 10a A = ON
If mu_a_c * ≤ carrier for power supply 10a, A = OFF
If mu_a_c * ≥ carrier for power supply 10a, E = OFF
mu_a_c_up * ≤ Carrier for power supply 10a E = ON
Thus, by generating the drive signal, a dead time of Td can be provided between A and E, and a short circuit between the positive electrodes can be prevented.

Further, the pulse generation method when outputting a voltage pulse from the power supply 10b is the same as that of the power supply 10a, and the following mu_b_c_up * and mu_b_c_down * are obtained and compared with the carrier for the power supply 10b (FIG. 10).
mu_b_c_up * = mu_b_c * + Hd
mu_b_c_down * = mu_b_c * − Hd
The drive signals for the D and C switches are obtained according to the following rules.
If mu_b_c_down * ≥ carrier for power supply 10b, D = ON
If mu_b_c * ≤ carrier for power supply 10b, D = OFF
If mu_b_c * ≥ carrier for power supply 10b, C = OFF
If mu_b_c_up * ≤ carrier for power supply 10b, C = ON
In this way, a dead time of Td can be provided between D and C, and a short circuit between the positive electrodes can be prevented. The drive signal B is generated from the AND of the drive signals E and C generated using an AND circuit or the like.
B = E ・ C
E is a drive signal with a dead time added to A, and C is a drive signal with a dead time added to D. For this reason, by generating B from AND of E and C using an AND circuit or the like, it is possible to generate dead times for B and A and B and E as well. An example of pulse generation with a dead time added is shown in FIG.

  When the drive signal with the dead time added is generated as described above and the modulation factor command values mu_a_c * and mu_b_c * are both 0, as shown in FIG. 13, both the drive signals E and C are turned off. A section 101 appears. When current flows from the motor to the power source, when both are turned off, a voltage is generated at the terminal by the differential value of the motor inductance and current. In this way, when a drive signal for turning off both of the semiconductor switches is given, the withstand voltage of the semiconductor switch must be a value that also assumes this voltage.

この式は、オフセット値から決まる出力可能な変調率の最大値から、デッドタイム相当の値をひいたものである。 An object of the present invention is to always secure a path from a motor to a DC power source by on / off control of a semiconductor switch, suppress a voltage generated at a terminal, and reduce the cost of the semiconductor switch. This will be described with reference to FIG. 12 has a configuration in which a modulation rate limiter 46a is added after the modulation rate correction means 46 of FIG. 5, and the operation and configuration other than 46a are the same as those described above (limiter of the second invention, 11th). Modulation rate limiter). The modulation rate limiter 46a is a limiter that sets and limits an upper limit value for the modulation rate. The upper limit value mu_a_c_max is obtained as the following value.

This equation is obtained by subtracting a value corresponding to the dead time from the maximum value of the modulation rate that can be output determined from the offset value.

  FIG. 14 shows a pulse generation result when the modulation factor command value shown in FIG. 13 is passed through the modulation factor limiter 46a. In FIG. 14, the maximum value of the modulation rate is limited to −Hd, and as a result, it is possible to secure a section 102 in which both the drive signals E and C are on. This corresponds to the effect of the second and twelfth inventions.

A second embodiment (corresponding to the fourth, sixth, seventh, eighth and ninth inventions) will be described below. In the second embodiment, the procedure and configuration are the same up to the modulation rate correction means 46 of the first embodiment, and differences after the PWM pulse generation means 47 will be described. When a dead time is added to the A and E drive signals and generated, an E drive signal E1 that is recognized to be turned on simultaneously with A is generated. The mu_a_c_down2 * used for the generation of E1 is obtained as follows (pulse voltage generation means permitting short circuit between the same polarity).
mu_a_c_down2 * = mu_a_c * − 2Hd
The carrier and mu_a_c_down2 * are compared, and the drive signal E1 is obtained according to the following rule.
If mu_a_c_down2 * ≥ carrier for power supply 10a E1 = OFF
If mu_a_c_down * ≤ carrier for power supply 10a E1 = ON
The drive signals A, E and E1 generated in this way are shown in FIG. Similarly, when a drive signal for the D and C switches is generated, a C drive signal C1 that is confirmed to be turned on simultaneously with D is generated.
mu_b_c_down2 * = mu_b_c * − 2Hd
If mu_b_c_down2 * ≧ carrier for power supply 10b, C1 = OFF
If mu_b_c_down * ≤ carrier for power supply 10b, C1 = ON
The drive signals E1 and C1 generated in this way cause a short circuit between the positive electrodes of the power supply. However, depending on the magnitude relationship of the power supply voltage, no short circuit current flows even if one of the paths between the positive electrodes is short-circuited. For example, when Vdc_a> Vdc_b, even if D and C are simultaneously turned on, this path is blocked by the semiconductor switch, so no short-circuit current flows. When Vdc_a <Vdc_b, A and E are simultaneously on. Even if there is, no short-circuit current flows. Further, if the potential difference between Vdc_a and Vdc_b is small, a large short-circuit current does not flow even if any of the paths A and E and C and D is short-circuited. Based on this idea, the voltage magnitude relationship is determined, and a path that permits a short circuit between the positive electrodes is selected.

The voltage Vdc_a of the power supply 10a and the voltage Vdc_b of the power supply 10a are detected, and a voltage discrimination signal is generated. The voltage discrimination signal is Vdc_b> Vdc_a and is an H signal. In this determination, a threshold value is set so that hysteresis control can be performed, and chattering of each switch due to switching of the determination signal due to noise superimposed on the signal of the voltage sensor is prevented. When the hysteresis width used as the threshold is Vhs, the voltage determination signal is generated as follows.
If Vdc_b> Vdc_a + Vhs, the voltage determination signal L is switched to H. If Vdc_b <Vdc_a−Vhs, the voltage determination signal H is switched to L. The hysteresis width Vhs is determined by observing the magnitude of noise in the voltage signal (the ninth). Equivalent to the invention).

The voltage determination signal generated in this way and the drive signals E · E1, C · C1 generated by the above-described method are input to the logic circuit shown in FIG. A drive signal that is not permitted is selected (corresponding to the sixth, seventh, and eighth inventions).
When the voltage determination signal is H, the logical OR of E and E1 is taken, a new drive signal E2 is output, and this drive signal E2 becomes the E drive signal. At this time, since E1 is generated longer than the ON pulse of E, E2 is equal to E1, and thus E1 is selected as the drive signal for E. C2 outputs C.
When the voltage determination signal is L, E is selected and output as E2, and C2 outputs C1. The drive signals E2 and C2 thus generated are replaced with the drive signals E and C, and are used to turn on / off each switch.

By permitting a short circuit between the positive electrodes according to the voltage, a current path from the output terminal of the power converter to one of the positive electrodes can be secured. In FIG. 18, the voltage determination signal is H, and the command value of the modulation factor is mu_b_c * = mu_a_c * = 0. At this time, the ON times of E and C are secured by the present invention as indicated by 105, A current path to the positive electrode is secured.
In this way, the path from the motor to the DC power supply is always secured by the on / off control of the semiconductor switch, the voltage generated at the end of the switch is suppressed, and the cost of the semiconductor switch can be reduced. .

  A third embodiment will be described below. In the third embodiment, the drive signals E and C generated by the configuration not using 46a of the first embodiment, the second embodiment, or the first embodiment are input, and the direction from the motor to the DC power source is input. 17 is a circuit that newly outputs drive signals E and C that secure a current path to the circuit, and is configured by the logic circuit of FIG. When both the drive signal E and the drive signal C are OFF and are L signals, the output of the NOR signal NOR is H. If this is ORed with the original drive signal E, the new drive signal E to be output becomes H. That is, by passing a signal through this circuit, when both E and C are off signals, it is possible to secure a current path from the motor to the power source by turning on E.

Further, when the power source 10b is a rechargeable secondary battery and the power source 10a is a non-chargeable power source, for example, a DC generator, if both the drive signals E and C which are inputs to the circuit of FIG. E keeps on. At this time, when the switch from the power source to the motor is also kept off, the power source 10b is charged by the induced voltage of the motor.
Conversely, when the power supply 10b is a power supply that cannot be charged, if the state of each switch as described above continues, only the smoothing capacitor is charged and this voltage rises, thus protecting the circuit elements from the voltage rise. It is necessary to provide a means for this. In this way, if a signal in the logic circuit is selected so that a current path from the motor to the regenerative power supply can be secured, an unnecessary voltage rise of the smoothing capacitor is not caused, and a control device such as protection associated therewith can be provided. This can be simplified (corresponding to the eleventh invention).

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention.

It is a figure which shows the structure of the conventional motor control system. It is a block diagram which shows an example of the fundamental structure of the power converter device by this invention. It is a block diagram which shows an example of the motor control system suitable for use of the control method of the power converter device by this invention. It is a block diagram which shows an example of the power converter which is a part of this invention. 3 is a configuration diagram extracted a part. It is a flowchart which shows the calculation of each block of FIG. It is a figure which shows the calculation in the PWM pulse production | generation means of 1st Example. It is the block diagram which extracted only the U phase from FIG. It is a figure which shows the pulse generation of A and E by a triangular wave comparison. It is a figure which shows the pulse generation of D and C by a triangular wave comparison. It is a figure which shows the example of the pulse generation to which the dead time was added. It is a block diagram of the control system which added the modulation factor limiter to FIG. It is a figure which shows an example of the pulse generation by the control system of FIG. It is a figure which shows an example of the pulse generation by the control system of FIG. It is a figure which shows the pulse generation of A and E by the triangular wave comparison which permitted the short circuit of the same polarity. It is a circuit diagram which performs selection of a drive signal. It is a circuit diagram of the drive signal processing in the third embodiment. It is a figure which shows an example of the pulse production | generation in a 2nd Example.

Explanation of symbols

1 Multiple DC power supplies
2 Power converter
2a Voltage generation means
2b Means of judgment
2c Route securing means
2d Limit value calculation means
2e Voltage limiting means
2f Short-circuit prevention pulse generation means
2g Short-circuit permission pulse generation means
2h Signal output means
3 Load including motor
10a, 10b power supply
12,13 Smoothing capacitor
14 Positive bus of power supply 10a
15 Common negative electrode bus
16 Power supply 10b positive bus
20 Motor
101a / 101b, 102a / 102b, 103a / 103b Semiconductor switch
104a / 104b, 105a / 105b, 106a / 106b semiconductor switch
107a, 108a, 109a Semiconductor switch
107b, 108b, 109b Diode
30 Power converter
30U U-phase switch group
30V V-phase switch group
30W W phase switch group
40 Control unit
41 Torque control means
42 Current control means
43 dq / 3-phase voltage conversion means
44 Voltage distribution means
45 Modulation rate calculation means
46 Modulation rate correction means
47 PWM pulse generation means
48 Three-phase / dq voltage conversion means
46a Modulation rate limiter

Claims (10)

The continuity from each of the plurality of DC power supplies to the multiphase AC motor is disconnected and the voltage pulses are generated and synthesized from the output voltages of the plurality of DC power supplies to generate a drive voltage to drive the multiphase AC motor. A first switch group;
A second switch group for connecting and disconnecting conduction from the load including the multiphase AC motor to each of the plurality of DC power sources;
For each phase, a method for controlling a power converter,
A path securing step in which at least one second switch group is always in a conductive state in each phase, and a current path from a load including the multiphase AC motor to at least one DC power source is secured in each phase;
The control method of the power converter device characterized by including. In the control method of the power converter device according to claim 1,
The path securing step controls the second switch based on at least one of a motor voltage command value of each phase or a command signal of a generated pulse. In the control method of the power converter device according to claim 1,
The path securing step calculates a limit value of a voltage command value of each phase motor, and controls the second switch based on the limited voltage command value of each phase. Control method. In the control method of the power converter device according to claim 1,
The path securing step includes at least one of the second switch groups in each phase when the second switch group is all off for each phase based on all drive signals of the second switch group. A method for controlling the power conversion device, wherein the power is turned on. In the control method of the power converter device according to claim 1,
A short-circuit prevention switch drive pulse generation step for generating a switch drive pulse command signal that prevents a short circuit of the inter-electrode paths having different potentials with respect to the first switch group and the second switch group in each phase;
A short-circuit permission switch drive pulse generating step for generating a switch drive pulse command signal that permits short-circuit between the same polarity for the second switch group in each phase, and
The path securing step outputs a switch drive pulse command signal that prevents the short circuit to the first switch group, and also allows a switch drive pulse that permits the second switch group to be short-circuited between the same polarities. A control method for a power converter, comprising a signal output step of selecting and outputting a command signal. In the control method of the power converter device according to claim 1,
A short-circuit prevention switch drive pulse generation step for generating a switch drive pulse command signal that prevents a short circuit of the inter-electrode paths having different potentials with respect to the first switch group and the second switch group in each phase;
A determination step of determining that the second switch group is all off for each phase from all of the switch drive pulse command signals that prevent the short circuit with respect to the second switch group, and
The path securing step is a switch operation that turns on at least one of the second switch groups in each phase when it is determined in the determining step that the second switch group is all off for each phase. A method for controlling a power conversion apparatus, comprising: a step. In the control method of the power converter device according to claim 5 or 6,
In the path securing step, the second switch provided in the path from the load including the multiphase AC motor to the DC power source having a large voltage is turned on based on the comparison of the voltage values of the plurality of DC power sources. A method for controlling a power conversion device. Two DC power supplies are provided, and the negative electrode of the first DC power supply and the negative electrode of the second DC power supply of the two DC power supplies are connected, and pulses are generated and synthesized from the output voltages of these DC power supplies. A control method for a power conversion device that generates a drive voltage to drive an AC motor,
In the path of conduction from the positive electrode of the first DC power source to a second DC power supply positive electrode, a switch between the output terminals of the power converter to the positive pole of the first DC power source, an output terminal of said power converter And a first short-circuit prevention time generating step of switching any of the switch sets from OFF to ON after a predetermined time when both of the switches between the switch and the positive electrode of the second DC power supply are turned off. ,
In the path of conduction from the positive electrode of the first DC power source to a second DC power supply positive electrode, a switch between the output terminals of the power converter to the positive pole of the first DC power source, an output terminal of said power converter A first path securing time generation step of switching any one of the switch sets from on to off after a predetermined time when both of the switches between the switch and the positive electrode of the second DC power source are on. ,
In the path of conduction from the positive electrode of the second DC power supply to the first DC power supply positive electrode, a switch between the output terminal of the second positive electrode and the power converter of a DC power source, an output terminal of said power converter A second short-circuit prevention time generating step of switching any of the switch sets from OFF to ON after a predetermined time when both sets of switches between the positive electrode of the first DC power supply and the switch are turned off;
In the path of conduction from the positive electrode of the second DC power supply to the first DC power supply positive electrode, a switch between the output terminal of the positive electrode and the power conversion device of the second DC power source, an output terminal of said power converter A second path securing time generation step of switching any of the switch sets from on to off after a predetermined time when both of the switch sets between the positive electrode of the first DC power source and the first set have passed.
When the positive potential of the first DC power supply is greater than the positive potential of the second DC power supply, control is performed so that the pulse generation by the first short-circuit prevention time generation step and the second path securing step is selected and output. When the positive potential of the first DC power supply is smaller than the positive potential of the second DC power supply, the pulse generation by the first path securing time generation step and the second short-circuit prevention time generation step is selected and output. A signal output step for controlling
The on-pulse of the switch between the output terminal of the power converter and the negative electrode is output from the power converter using the result of pulse generation by the first short-circuit prevention time generation step and the second short-circuit prevention time generation step. A switch between the terminal and the positive electrode of the second DC power supply and a switch between the output terminal of the power converter and the positive electrode of the first DC power supply are controlled to be generated when both are on. Control steps;
The control method of the power converter device characterized by including. In the control method of the power converter device according to claim 7 or 8 ,
When comparing the magnitudes of the voltage values of the plurality of DC power supplies, a threshold value capable of performing hysteresis control is used.
A method for controlling a power conversion device. In the control method of the power converter device according to claim 3,
The motor voltage command value for each phase is a modulation rate command value in which the voltage command value is standardized by the power supply voltage, and the short-circuit prevention time of each switch, the voltage value of each AC power supply, and the power ratio of each AC power supply Based on the above, find the limit value of the motor voltage command value for each phase.
A method for controlling a power conversion device.

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