Power generation system and electric drive system using it

Abstract

To provide a power generation system capable of suppressing fluctuation of DC voltage obtained from a main winding of a two-winding induction generator and fluctuation of DC voltage obtained from an auxiliary winding by one power converter.SOLUTION: A control unit 11 is configured to perform the steps of: calculating a state quantity KR that changes according to fluctuations in the required power of a load 4 connected to a rectifier 3 or a power converter 7; based on the state quantity KR, calculating a first voltage correction value ΔVmDC* for compensating for fluctuations in a first DC voltage VmDC and a second voltage correction value ΔVaDC* for compensating for fluctuations in a second DC voltage VaDC; adding the first voltage correction value ΔVmDC* to a command value VmDC* of the first DC voltage VmDC; and adding the second voltage correction value ΔVaDC* to a command value VaDC* of the second DC voltage VaDC.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a power generation system including a two-winding induction generator and an electric drive system using the same.

Background Art

[0002] A system for controlling a rotating machine with a plurality of windings is known. For example, in Patent Document 1, in a drive control device for a multi-winding motor having a plurality of winding groups, for each winding group of the multi-winding motor, a power converter for driving the winding group is provided, and a signal of a first control unit for controlling a first power converter for driving a first winding group among the winding groups is used to obtain a compensation amount for compensating a signal of another control unit for controlling other power converters other than the first power converter. A compensation amount calculation unit is provided, and the other control unit is a control system having a waste time in control. The other power converter is controlled by compensating the signal of the other control unit with the compensation amount obtained by the compensation amount calculation unit, and the first power converter is controlled without compensating the signal of the first control unit. Thus, interference between winding groups can be suppressed and the control system can be stabilized even in a control configuration of one-way communication, and a drive control device for a multi-winding motor with a simple configuration is provided.

[0003] Also, in Patent Document 2, in a control device applied to a multi-winding rotating machine system including a multi-winding rotating machine having a plurality of winding groups with equivalent electrical specifications, a plurality of power converters provided for each of the plurality of winding groups, and a current detector, a non-interference unit performs a non-interference control operation for compensating an interference voltage due to magnetic coupling. The non-interference unit "integrates" a non-interference control term including a mutual inductance and a current derivative value related to a post-controller command current of a target axis of another system into an inverse model term related to a post-controller command current of a target axis of its own system, and an angular velocity and a self-inductance included in a non-interference control term related to a post-controller command current of a non-target axis of its own system, and an angular velocity and a mutual inductance included in a non-interference control term related to a post-controller command current of a non-target axis of another system. By doing so, a control device for a multi-winding rotating machine that simplifies the control configuration of the non-interference unit and reduces the calculation load is provided.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-101090 [Patent Document 2] Japanese Patent Publication No. 2016-149904 [Overview of the project] [Problems that the invention aims to solve]

[0005] In an induction generator equipped with a stator having a main winding and an auxiliary winding (a two-winding induction generator), the main winding and the auxiliary winding are magnetically coupled. Therefore, if the power demand of the load connected to the main winding fluctuates according to operator operations, the DC voltage obtained from the main winding fluctuates, and consequently, the DC voltage obtained from the auxiliary winding also fluctuates.

[0006] In the drive control device for a multi-winding motor described in Patent Document 1, a power converter is provided for each winding of the multi-winding motor, and interference between windings is suppressed by compensating the signals of other control units that control power converters other than the first power converter using the command value of the first power converter. However, there is no description of a means to suppress voltage fluctuations that occur in each winding when disturbances occur. Furthermore, since a power converter is provided for each winding, it is necessary to secure space for each of these units.

[0007] Furthermore, the multi-winding rotating machine system described in Patent Document 2 also has a configuration in which a power converter is provided for each winding of the multi-winding rotating machine, so, similar to Patent Document 1, it is necessary to secure space for the number of power converters. Moreover, there is no description of means for suppressing voltage fluctuations that occur in each winding when disturbances occur.In addition, the technique for simplifying the control configuration of the deinterference section disclosed in Patent Document 2 is based on the premise that the electrical specifications of each winding are equivalent to each other, and therefore cannot be applied to multi-winding rotating machines in which the electrical specifications of each winding are different.

[0008] The present invention has been made in view of the above problems, and its objective is to provide a power generation system and an electric drive system using the same that can suppress fluctuations in the DC voltage obtained from the main winding and the DC voltage obtained from the auxiliary winding of a two-winding induction generator with a single power converter. [Means for solving the problem]

[0009] To achieve the above objective, the present invention provides a power generation system comprising: a generator having a stator including a main winding and an auxiliary winding; a rectifier connected to the main winding and converting the AC voltage generated by the main winding into a first DC voltage; a power converter connected to the auxiliary winding and controlling the voltages of the main winding and the auxiliary winding, and converting the AC voltage generated by the auxiliary winding into a second DC voltage; and a control device that controls the power converter according to the command values ​​of the first DC voltage and the second DC voltage, wherein the control device changes in accordance with fluctuations in the power demand of the load connected to the rectifier or the power converter. The value of the change per unit time State variables as Calculate, and based on the above state variables, Due to fluctuations in the power requirements of the aforementioned load A first voltage correction value that compensates for the fluctuation of the first DC voltage, and Due to fluctuations in the power requirements of the aforementioned load A second voltage correction value is calculated to compensate for the fluctuation of the second DC voltage, and the first voltage correction value is added to the command value of the first DC voltage. The value and The second voltage correction value is added to the command value of the second DC voltage. A control signal is generated based on the obtained value, and the power converter is controlled by the control signal. It shall be considered as such.

[0010] As described above, the present invention, configured as described above, allows a power converter that controls the voltages of the main winding and the auxiliary winding to compensate for fluctuations in the DC voltage obtained from the main winding (first DC voltage) and the DC voltage obtained from the auxiliary winding (second DC voltage) in response to fluctuations in the power demand of the load. This makes it possible to suppress fluctuations in the DC voltage obtained from the main winding and the DC voltage obtained from the auxiliary winding with a single power converter. [Effects of the Invention]

[0011] According to the present invention, in a power generation system equipped with a two-winding induction generator, or an electric drive system using said power generation system, it is possible to suppress fluctuations in the DC voltage obtained from the main winding and the DC voltage obtained from the auxiliary winding with a single power converter. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows the configuration of a dump truck in the first embodiment of the present invention. [Figure 2] This figure shows the configuration of the electric drive system in the first embodiment of the present invention. [Figure 3] These are a side view and a partially enlarged cross-sectional view showing the structure of a two-winding induction generator in the first embodiment of the present invention. [Figure 4] This is a functional block diagram of the control device in the first embodiment of the present invention. [Figure 5] This is a block diagram showing the processing of the current command calculation unit and the voltage command calculation unit in the first embodiment of the present invention. [Figure 6] This is a block diagram showing the processing of the frequency command calculation unit in the first embodiment of the present invention. [Figure 7] This is a block diagram showing the processing of the voltage command compensation unit in the first embodiment of the present invention. [Figure 8] This is a block diagram showing a modified example of the processing of the voltage command compensation unit in the first embodiment of the present invention. [Figure 9] This is a block diagram showing the processing of the DC voltage command correction unit in the first embodiment of the present invention. [Figure 10] This figure shows the relationship between the state variable and the DC voltage command correction value in the first embodiment of the present invention. [Figure 11] This figure shows the time-series changes of each parameter of the power generation system in the first embodiment of the present invention. [Figure 12] This figure shows the waveforms of the main winding current and auxiliary winding current of a two-winding induction generator when a disturbance occurs in the main load in the first embodiment of the present invention. [Figure 13]It is a diagram showing the configuration of an electric drive system in a second embodiment of the present invention. [Figure 14] It is a block diagram showing the processing of a DC voltage command correction unit in a second embodiment of the present invention. [Figure 15] It is a block diagram showing the processing of a DC voltage command correction unit in a third embodiment of the present invention.

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, equivalent elements are denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. Further, although this embodiment applies the power generation system according to the present invention to the electric drive system of a dump truck, the application target of the present invention is not limited to this.

Example

[0014] FIG. 1 shows the configuration of a dump truck in a first embodiment of the present invention. In FIG. 1, the dump truck includes a vehicle body 30, a prime mover 1, a loading platform 31 rotatably attached in the vertical direction to the upper rear of the vehicle body 30, and a driver's seat 32 provided at the upper front of the vehicle body 30. Further, a pair of left and right driven wheels 33 are arranged on the lower front side of the vehicle body 30, and a pair of left and right drive wheels 34 are arranged on the lower rear side of the vehicle body 30. The drive wheels 34 are driven by a traveling motor 5.Mining dump trucks repeat a series of work cycles of loading earth and sand at the loading site, traveling from the loading site to the dumping site, dumping at the dumping site, and traveling from the dumping site to the loading site.

[0015] Figure 2 is a diagram showing the configuration of the electric drive system mounted on the dump truck shown in Figure 1. In Figure 2, the electric drive system comprises a prime mover 1, a two-winding induction generator 2 equipped with a stator having a main winding and an auxiliary winding, a rectifier 3, a drive inverter 4, a drive motor 5, a regenerative discharge resistor 6, a power converter 7, an auxiliary inverter 8, an auxiliary motor 9, a starting battery 10, a control device 11, a first voltage sensor 12, a first current sensor 13, a first rotation sensor 14, a second voltage sensor 15, a second current sensor 16, a third voltage sensor 17, a second rotation sensor 50, and a torque sensor 51. Here, the prime mover 1, the two-winding induction generator 2, the rectifier 3, the power converter 7, the control device 11, the first voltage sensor 12, the first current sensor 13, the first rotation sensor 14, the second voltage sensor 15, the second current sensor 16, and the third voltage sensor 17 constitute the power generation system 40 in this embodiment.

[0016] The prime mover 1 rotates the rotor of the two-winding induction generator 2. The main winding of the two-winding induction generator 2 is connected to the traction inverter 4 via the rectifier 3. The traction inverter 4 is connected to the traction motor 5. The regenerative discharge resistor 6 is connected to the rectifier 3 and the traction inverter 4 when the traction motor 5 is generating power. The auxiliary winding of the two-winding induction generator 2 is connected to the auxiliary inverter 8 via the power converter 7. The auxiliary inverter 8 is connected to the auxiliary motor 9. The starting battery 10 is connected to the power converter 7 and the auxiliary inverter 8 when the two-winding induction generator 2 is running.

[0017] Here, the output of the traction motor 5 is greater than the output of the auxiliary motor 9, and the power requirement of the traction inverter 4 is greater than the power requirement of the auxiliary inverter 8. Therefore, by connecting the power converter, which is more expensive than a rectifier, to the auxiliary inverter 8, which has a lower power requirement, instead of the traction inverter 4, the power converter can be made smaller in capacity, and the cost of the electric drive system can be reduced.

[0018] Figure 3 shows a side view and a partially enlarged cross-sectional view illustrating the structure of a two-winding induction generator 2 in this embodiment. The two-winding induction generator 2 comprises a stator 210 and a rotor 220. The stator 210 has a primary winding 213 installed in stator slots 212 formed by a stator core 211, and the primary winding 213 has a main winding 2131 and an auxiliary winding 2132. The primary winding 213 is held in the stator slots 212 by wedges 214. The rotor 220 has rotor bars 2231 installed in rotor slots 222 formed by a rotor core 221, and the ends of the rotor bars 2231 are short-circuited by end rings 2232. The secondary conductor 223 has rotor bars 2231 and end rings 2232. The gap 230 is the air gap between the stator 210 and the rotor 220.

[0019] Next, with reference to Figure 4, the configuration of the control device 11 that controls the power converter 7 will be described. In Figure 4, the control device 11 consists of a 3-phase / 2-phase conversion unit 18a, 18b, 18c, a current command calculation unit 19, a frequency command calculation unit 20, a voltage command calculation unit 21, a voltage command compensation unit 22, a turns ratio conversion unit 23, a DC voltage command correction unit 24, a 2-phase / 3-phase conversion unit 25, and a control signal generation unit 26. The control device 11 consists of a controller with calculation processing functions, an input / output interface that performs signal input / output with external devices, etc., and realizes the functions of each unit by executing a program stored in a storage device such as ROM. In this embodiment, the control device 11 controls the voltage and current of the main winding and auxiliary winding via the power converter 7 so that the main-side DC voltage VmDC and the auxiliary-side DC voltage VaDC match the corrected main-side DC voltage command value VmDC** and the corrected auxiliary-side DC voltage command value VaDC**, respectively.

[0020] Voltage control is performed by the current command calculation unit 19 using values ​​obtained from the first voltage sensor 12 and the third voltage sensor 17 (main engine DC voltage VmDC, auxiliary engine DC voltage VaDC) to perform a proportional-integral calculation, for example, and output auxiliary winding current command values ​​Iad*, Iaq*. Current control is performed by the voltage command calculation unit 21 using values ​​obtained from the first current sensor 13 (auxiliary winding 3-phase currents Iau, Iav, Iaw) to perform a coordinate transformation on the dq axis by the 3-phase / 2-phase conversion unit 18c to obtain values ​​(d-axis auxiliary winding current Iad, q-axis auxiliary winding current Iaq) to perform a proportional-integral calculation, for example, and output auxiliary winding voltage command values ​​Vad*, Vaq*. The voltage command calculation unit 21 uses the value ωr obtained from the rotation sensor 14 and the frequency command value ω1* to compensate for the induced voltage generated by the rotation of the rotor of the two-winding induction generator 2 and the interference component between the dq axes, respectively.

[0021] Figure 5 is a block diagram showing the processing of the current command calculation unit 19 and the voltage command calculation unit 21. The current command calculation unit 19 proportionally integrates the difference between the corrected main engine-side DC voltage command value VmDC** and the DC voltage VmDC, and outputs it as the d-axis auxiliary winding current command value Iad*. In the figure, Kmv_p is the main engine-side voltage control proportional gain, and Kmv_i is the main engine-side voltage control integral gain.

[0022] Furthermore, the current command calculation unit 19 proportionally integrates the difference between the corrected auxiliary DC voltage command value VaDC** and the DC voltage VaDC, and outputs it as the d-axis auxiliary winding current command value Iad*. In the figure, Kav_p is the auxiliary voltage control proportional gain, and Kav_i is the auxiliary voltage control integral gain.

[0023] The voltage command calculation unit 21 subtracts the interference component occurring between the d and q axes from the proportional integral of the difference between the d-axis auxiliary winding current command value Iad* and the d-axis auxiliary winding current Iad, and outputs it as the d-axis auxiliary winding voltage command value Vad*. The interference component occurring between the d and q axes is obtained by multiplying the integral of the difference between the d-axis auxiliary winding current command value Iad* and the d-axis auxiliary winding current Iad by ω1*Lσm / Rσa. In the figure, Kmc_p is the main engine side current control proportional gain, and Kmc_i is the main engine side current control integral gain.

[0024] Furthermore, the voltage command calculation unit 21 adds the interference component occurring between the dq axes and the induced voltage ωr*μ*φ2d to the proportional integral of the difference between the q-axis auxiliary winding current command value Iaq* and the q-axis auxiliary winding current Iaq, and outputs it as the q-axis auxiliary winding voltage command value Vaq*. The interference component occurring between the dq axes is obtained by multiplying the integral of the difference between the q-axis auxiliary winding current command value Iaq* and the q-axis auxiliary winding current Iaq, using the auxiliary current control integral gain Kac_i, by ω1*Lσm / Rσa. In the figure, Kac_p is the auxiliary current control proportional gain, and Kac_i is the auxiliary current control integral gain.

[0025] Figure 6 is a block diagram showing the processing of the frequency command calculation unit 20. The frequency command calculation unit 20 adds the frequency command value ω1* calculated by the slip frequency command calculation unit 20a to the frequency ωr obtained from the rotation sensor 14, and outputs the frequency command value ω1*.

[0026] Next, the role of the voltage command compensation unit 22 will be explained. In the two-winding induction generator 2, interference components are generated between the windings due to the magnetic coupling of the main winding and the auxiliary winding. This phenomenon can be explained using the differential equation for the auxiliary winding section of the two-winding induction generator 2, shown in Equation 1.

[0027]

number

[0028] The symbols used in Mathematical Formula 1 are as follows:

[0029] Rσm: Main winding resistance related to auxiliary windings in the dq axis model Auxiliary winding resistance in the Rσa:dq axis model Lσm: Main winding self-inductance related to auxiliary winding in dq axis model Auxiliary winding self-inductance related to the auxiliary winding in the Lσa:dq axis model μ: Primary conversion factor for auxiliary windings τ²: Secondary time constant (= secondary inductance / secondary resistance) p: differential operator Imd,Imq: d-axis main winding current, q-axis main winding current Vmd, Vmq: d-axis main winding voltage, q-axis main winding voltage Vad, Vaq: d-axis auxiliary winding voltage, q-axis auxiliary winding voltage φ2d, φ2q: d-axis secondary magnetic flux, q-axis secondary magnetic flux ω1: Primary frequency By rearranging equation 1, we obtain equation 2.

[0030]

number

[0031] From equation 2, it can be seen that the auxiliary winding voltage includes the main winding currents Imd, Imq and main winding voltages Vmd, Vmq on the dq axis. These terms related to the main winding current and main winding voltage are interference components of the main winding with respect to the auxiliary winding, and cause instability in controlling the two-winding induction generator 2. Therefore, by compensating for this interference component with the control device 11, the two-winding induction generator 2 can be controlled stably even when there is magnetic coupling between the main winding and the auxiliary winding. Specifically, the auxiliary winding voltage command values ​​Vad*, Vaq* calculated by the voltage command calculation unit 21 are added to the voltage compensation amounts ΔVad*, ΔVaq* calculated by the voltage command compensation unit 22, respectively, and the compensated auxiliary winding voltage commands Vad**, Vaq** are input to the turns ratio conversion unit 23.

[0032] The turns ratio conversion unit 23 multiplies the compensated auxiliary winding voltage commands Vad** and Vaq** by the ratio of the main winding self-inductance Lσm related to the auxiliary winding in the dq-axis model to the auxiliary winding self-inductance Lσa related to the auxiliary winding in the dq-axis model. The auxiliary winding voltage commands Vad*** and Vaq*** converted by the turns ratio conversion unit 23 are input to the 2-phase / 3-phase conversion unit 25, which converts from 2-phase to 3-phase, and the converted 3-phase voltage command values ​​Vau*, Vav*, and Vaw* are input to the control signal generation unit 26. Here, in the 3-phase / 2-phase conversion units 18a, 18b, 18c and the 2-phase / 3-phase conversion unit 25, the phase used for coordinate transformation is, for example, a value obtained by integrating the frequency command value ω1*. The control signal generation unit 26 generates a control signal to be transmitted to the power converter 7, for example, based on a comparison between the duty cycle signal calculated from the three-phase voltage command values ​​Vau*, Vav*, Vaw* and the carrier wave.

[0033] Figure 7 is a block diagram showing the processing of the voltage command compensation unit 22. The values ​​obtained from the second voltage sensor 15 and the second current sensor 16 (three-phase currents Imu, Imv, Imw of the main winding and three-phase voltages Vmu, Vmv, Vmw of the main winding) are coordinate-transformed by the three-phase / two-phase conversion units 18a and 18b, respectively, and the coordinate-transformed values ​​(Imd, Imq, Vmd, Vmq) are used as input to the voltage command compensation unit 22. The d-axis voltage compensation amount ΔVad* is the difference between the d-axis main winding voltage Vmd and the product of the d-axis main winding current Imd and the main winding resistance Rσm related to the auxiliary winding, and the q-axis voltage compensation amount ΔVaq* is the difference between the q-axis main winding voltage Vmq and the product of the q-axis main winding current Imq and the main winding resistance Rσm related to the auxiliary winding. By directly using the values ​​obtained from voltage sensors 15 and 16 in this way, the compensation voltage amounts ΔVad* and ΔVaq* can be calculated without any calculation delay.

[0034] Figure 8 is a block diagram showing the processing of the voltage command compensation unit when the second voltage sensor 15 is not used, which can be considered as a modified version of the processing shown in Figure 7. In Figure 8, the voltage command compensation unit 22 receives the auxiliary winding voltage command values ​​Vad*, Vaq* output from the voltage command calculation unit 21 as input, instead of the main winding voltages Vmd, Vmq detected by the second voltage sensor 15. The voltage command compensation unit 22 utilizes the property that the voltage of the main winding of the two-winding induction generator 2 is roughly proportional to the voltage of the auxiliary winding, and calculates estimated values ​​of the main winding voltages Vmd, Vmq by multiplying the auxiliary winding voltage command values ​​Vad*, Vaq* by a correction gain K (ratio of main winding voltage to auxiliary winding voltage). Even with this configuration, the same effect as the configuration in Figure 7 can be achieved, and since the second voltage sensor 15 that detects the main winding voltages Vmd, Vmq is not required, the configuration of the power generation system 40 can be simplified.

[0035] Next, the DC voltage command correction unit 24 will be explained. When the power demanded by the main engine increases rapidly, the main engine DC voltage VmDC decreases, and the current command calculation unit 19 increases the d-axis auxiliary winding current command value Iad* to raise the decreased main engine DC voltage VmDC. As a result, the auxiliary winding current increases, and the auxiliary engine DC voltage VaDC increases in the opposite direction to the main engine DC voltage VmDC. To suppress this transient fluctuation that occurs simultaneously in the main engine DC voltage VmDC and the auxiliary engine DC voltage VaDC, the DC voltage command correction unit 24 corrects the main engine DC voltage command value VmDC* and the auxiliary engine DC voltage command value VaDC*, respectively.

[0036] Figure 9 is a block diagram showing the processing of the DC voltage command correction unit 24. Based on the output result (state quantity KR) of the state quantity calculation unit 24a, the DC voltage command correction unit 24 calculates a correction value ΔVmDC* for the main engine side DC voltage command value VmDC* in the main engine side DC voltage command correction unit 24b, and calculates a correction value ΔVaDC* for the auxiliary engine side DC voltage command value VaDC* in the auxiliary engine side DC voltage command correction unit 24c. Here, the state quantity KR is a value that changes according to fluctuations in the power demand of the load connected to the rectifier 3 or power converter 7, and in this embodiment, it is a value that changes according to the power demand of the traction inverter 4.

[0037] The state quantity calculation unit 24a calculates, for example, the change in the product of the rotational speed ωm of the drive motor 5 and the torque command value Tm* to the drive motor 5 per unit time Δt as the state quantity KR (Equation 3), and uses this as input to the main engine side DC voltage command correction unit 24b and the auxiliary engine side DC voltage command correction unit 24c.

[0038]

number

[0039] In the method for calculating the state variable KR using equation 3, for example, if the rotational speed ωm of the drive motor 5 increases rapidly in relation to the torque command value Tm* of the drive motor 5, the state variable KR increases. This increase in the state variable KR means that the power demanded by the main engine side increases rapidly, and a transient voltage drop in the main engine side DC voltage VmDC can be detected in advance. Conversely, if the state variable KR becomes negative, it means that the power demanded decreases rapidly, and in this case the main engine side DC voltage VmDC increases transiently. Here, the torque command value Tm* of the drive motor 5 is used to calculate the state variable KR, but the torque detection value Tm detected by the torque sensor 51 may also be used.

[0040] The main engine-side DC voltage command correction unit 24b calculates a correction value ΔVmDC* for the main engine-side DC voltage command value VmDC* according to the map characteristics shown in Figure 10(a), based on the state quantity KR calculated by the state quantity calculation unit 24a. Figure 10(a) is an example of a map showing the relationship between the state quantity KR and the correction value ΔVmDC* for the main engine-side DC voltage command value VmDC*. In the map characteristics of Figure 10(a), the larger the slope, the larger the correction value ΔVmDC* for the main engine-side DC voltage command value VmDC* in the state quantity KR in the positive direction. These map characteristics are determined in advance by calculation or experiment. Also, in Figure 10(a), when the state quantity KR is negative, the correction value ΔVmDC* for the main engine-side DC voltage command value VmDC* is set to 0. In this embodiment, when the state quantity KR is negative, it is assumed that the drive motor 5 is regenerating. When the drive motor 5 regenerates power, the regenerative discharge resistor 6 turns ON and absorbs the regenerative power, thus suppressing the rise in the main engine DC voltage VmDC. Therefore, when the state variable KR is negative, the correction value ΔVmDC* of the main engine DC voltage command value VmDC* is set to 0, and no correction is performed on the main engine DC voltage command value VmDC*. However, in the case of a configuration that does not use the regenerative discharge resistor 6 used in this embodiment, the correction value ΔVmDC* of the main engine DC voltage command value VmDC* may be calculated using a map that also considers the case when the state variable KR is negative, as shown in Figure 10(b). By adding the correction value ΔVmDC* of the main engine DC voltage command value VmDC* calculated by the main engine DC voltage command correction unit 24b to the main engine DC voltage command value VmDC*, fluctuations in the main engine DC voltage VmDC can be suppressed.

[0041] The auxiliary DC voltage command correction unit 24c calculates a correction value ΔVaDC* for the auxiliary DC voltage command value VaDC* according to the map characteristics shown in Figure 10(c), based on the state quantity KR calculated by the state quantity calculation unit 24a. Figure 10(c) is an example of a map showing the relationship between the state quantity KR and the correction value ΔVaDC* for the auxiliary DC voltage command value VaDC*. In the map characteristics of Figure 10(c), the larger the slope, the larger the negative correction value ΔVaDC* for the auxiliary DC voltage command value VaDC* in the state quantity KR. These map characteristics are determined in advance by calculation or experiment. By adding the correction value ΔVaDC* for the auxiliary DC voltage command value VaDC* calculated by the auxiliary DC voltage command correction unit 24c to the auxiliary DC voltage command value VaDC*, fluctuations in the auxiliary DC voltage VaDC can be suppressed.

[0042] The main operation and effects of the power generation system 40 in this embodiment will be described below with reference to Figure 11. Figure 11 is a diagram showing the time-series changes of each parameter (state quantity KR, correction value ΔVmDC* for main-side DC voltage command value VmDC*, correction value ΔVaDC* for auxiliary-side DC voltage command value VaDC*, main-side DC voltage VmDC, and auxiliary-side DC voltage VaDC) of the power generation system 40 in this embodiment. An example of operation when the power demanded by the main engine changes will be described below. In addition, in order to clarify the effects of this embodiment, the operation will be described in comparison with the case where the main-side DC voltage command value VmDC* and the auxiliary-side DC voltage command value VaDC* are not corrected by the correction value ΔVmDC* for the main-side DC voltage command value VmDC* calculated by the main-side DC voltage command correction unit 24b and the correction value ΔVaDC* for the auxiliary-side DC voltage command value VaDC* calculated by the auxiliary-side DC voltage command correction unit 24c. It should be assumed that the change in the power demand on the main unit side is the same for the power generation system 40 in this embodiment and the power generation system in the comparative example.

[0043] In Figure 11, the time-series changes of each parameter in this embodiment are shown by solid lines, and the time-series changes of each parameter in the comparative example are shown by dashed lines. The horizontal axis in Figures 11(a) to (e) represents time (elapsed time). The vertical axis in Figure 11(a) represents the state variable KR, the vertical axis in Figure 11(b) represents the correction value ΔVmDC* of the main engine DC voltage command value VmDC*, the vertical axis in Figure 11(c) represents the correction value ΔVaDC* of the auxiliary engine DC voltage command value VaDC*, the vertical axis in Figure 11(d) represents the main engine DC voltage VmDC detected by the third voltage sensor 17, and the vertical axis in Figure 11(e) represents the auxiliary engine DC voltage VaDC detected by the first voltage sensor 12.

[0044] In Figure 11, time t0 is the time when the state variable KR begins to change. Time t1 is the time when the state variable KR reaches the required value and the change stops.

[0045] As shown in Figure 11(a), in this embodiment, the state variable KR increases in the positive direction as the torque Tm* or rotational speed ωm increases from time t0.

[0046] As shown in Figure 11(b), in this embodiment, from time t0, the correction value ΔVmDC* of the main engine DC voltage command value VmDC* increases in the positive direction as the state variable KR increases. As a result, while the state variable KR is increasing, the main engine DC voltage command value VmDC**, which is obtained by correcting the main engine DC voltage command value VmDC* with the correction value ΔVmDC* of the main engine DC voltage command value VmDC*, becomes the input to the current command calculation unit 19.

[0047] As shown in Figure 11(c), in this embodiment, from time t0, the correction value ΔVaDC* of the auxiliary DC voltage command value VaDC* increases in the negative direction as the state variable KR increases. As a result, while the state variable KR is increasing, the auxiliary DC voltage command value VaDC** obtained by correcting the auxiliary DC voltage command value VaDC* by the correction value ΔVaDC* of the auxiliary DC voltage command value VaDC* becomes the input to the current command calculation unit 19.

[0048] As shown in Figure 11(d), in the comparative example, immediately after the state variable KR begins to increase at time t0, the main engine DC voltage VmDC begins to decrease, but the current command calculation unit 19 operates to track the main engine DC voltage command value VmDC*, and therefore recovers.

[0049] In contrast, in this embodiment, the amount of decrease in the main engine DC voltage VmDC immediately after the change in state variable KR is reduced by correcting the main engine DC voltage command value VmDC* with a correction value ΔVmDC* corresponding to the increase in state variable KR from time t0.

[0050] As shown in Figure 11(e), in the comparative example, immediately after the state variable KR begins to increase at time t0, the auxiliary DC voltage VaDC begins to increase. This is because the current command calculation unit 19 increases the d-axis auxiliary winding current command value Iad* in order to increase the main engine DC voltage VmDC which has decreased, thereby increasing the auxiliary winding current. Immediately after the increase in state variable KR, the auxiliary DC voltage VaDC increases, but the current command calculation unit 19 operates to follow the auxiliary DC voltage command value VaDC*, and recovers with a proportional-integral response.

[0051] In contrast, in this embodiment, the auxiliary DC voltage command value VaDC* is corrected by a correction value ΔVaDC* of the auxiliary DC voltage command value VaDC* corresponding to the increase in state quantity KR from time t0, thereby reducing the increase in the auxiliary DC voltage VaDC immediately after the change in state quantity KR. In this way, by adding the correction value ΔVmDC* of the main engine DC voltage command value VmDC* and the correction value ΔVaDC* of the auxiliary DC voltage command value VaDC*, calculated based on the state quantity KR, to the main engine DC voltage command value VmDC* and the auxiliary DC voltage command value VaDC*, respectively, transient fluctuations in the main engine DC voltage VmDC and auxiliary DC voltage VaDC due to a sudden increase in the power demanded by the main engine can be suppressed.

[0052] Next, a method for verifying whether the configuration of this embodiment is correctly implemented in the power generation system 40 will be described. Since the configuration of this embodiment is likely to be implemented in software (the program of the control device 11), it is expected to be difficult to verify based on the appearance of the power generation system 40, etc. Therefore, the power generation system 40 will be operated and the verification will be performed based on its behavior.

[0053] When performing verification, for example, a current sensor is connected to the main winding side or the auxiliary winding side of a two-winding induction generator 2 (shown in Figure 2). Furthermore, a disturbance generator is connected to the main side of the two-winding induction generator 2 to vary the load, and the main winding current or auxiliary winding current is measured with the current sensor when a disturbance is generated by the disturbance generator. However, in this case, the main side DC voltage command value VmDC*, the auxiliary side DC voltage command value VaDC*, and the auxiliary side load are kept constant, and the disturbance generator on the main side is assumed to generate disturbances in a step-like manner.

[0054] Figure 12 shows the waveforms of the three-phase currents Imu, Imv, Imw of the main winding and the three-phase currents Iau, Iav, Iaw of the auxiliary winding when a disturbance occurs on the main winding side. Figure 12(a) shows the results when this embodiment is not applied, as a comparative example, and (b) shows the results when this embodiment is applied. From Figure 12(b), it can be seen that when this embodiment is applied, a transient response can be confirmed when a disturbance occurs, due to the correction value ΔVmDC* of the main winding DC voltage command value VmDC* and the correction value ΔVaDC* of the auxiliary winding DC voltage command value VaDC*. Conversely, when this embodiment is not applied, a transient response cannot be confirmed when a disturbance occurs. In this way, by measuring the main winding current or the auxiliary winding current in the two-winding induction generator 2, it is possible to verify whether or not the configuration of this embodiment is implemented.

[0055] (summary) In this embodiment, the power generation system comprises: a generator 2 having a stator including a main winding and an auxiliary winding; a rectifier 3 connected to the main winding and converting the AC voltage generated by the main winding into a first DC voltage VmDC; a power converter 7 connected to the auxiliary winding and controlling the voltages of the main winding and the auxiliary winding, and converting the AC voltage generated by the auxiliary winding into a second DC voltage VaDC; and a control device 11 that controls the power converter 7 according to the command value VmDC* of the first DC voltage and the command value VaDC* of the second DC voltage. In step 40, the control device 11 calculates a state variable KR that changes in accordance with fluctuations in the power demand of the load 4 connected to the rectifier 3 or power converter 7. Based on the state variable KR, it calculates a first voltage correction value ΔVmDC* to compensate for fluctuations in the first DC voltage VmDC, and a second voltage correction value ΔVaDC* to compensate for fluctuations in the second DC voltage VaDC. The first voltage correction value ΔVmDC* is added to the command value VmDC* of the first DC voltage VmDC, and the second voltage correction value ΔVaDC* is added to the command value VaDC* of the second DC voltage VaDC.

[0056] In this embodiment configured as described above, the power converter 7, which controls the voltages of the main winding and the auxiliary winding, compensates for fluctuations in the DC voltage (first DC voltage VmDC) obtained from the main winding and the DC voltage (second DC voltage VaDC) obtained from the auxiliary winding, ΔVmDC and ΔVaDC, in response to fluctuations in the power demand of the load 4. This makes it possible to suppress fluctuations in the DC voltage VmDC obtained from the main winding and the DC voltage VaDC obtained from the auxiliary winding with a single power converter 7.

[0057] Furthermore, the electric drive system in this embodiment includes a power generation system 40, a traction motor 5, and a traction inverter 4 which is a load connected to a rectifier 3 and converts the first DC voltage VmDC into an AC voltage and supplies it to the traction motor 5. This makes it possible to suppress fluctuations in the DC voltage VmDC obtained from the main winding and the DC voltage VaDC obtained from the auxiliary winding with a single power converter 7 in the electric drive system.

[0058] Furthermore, in this embodiment, the control device 11 calculates the state variable KR based on the torque Tm* and rotational speed ωm of the traction motor 5. This makes it possible to compensate for fluctuations in the DC voltage (first DC voltage VmDC) obtained from the main winding and the DC voltage (second DC voltage VaDC) obtained from the auxiliary winding, ΔVmDC and ΔVaDC, in response to fluctuations in the power demanded by the traction inverter 4. [Examples]

[0059] A second embodiment of the present invention will be described, focusing on the differences from the first embodiment.

[0060] Figure 13 is a diagram showing the configuration of the electric drive system in this embodiment. In Figure 13, the electric drive system comprises a prime mover 1, a two-winding induction generator 2 equipped with a stator having a main winding and an auxiliary winding, a rectifier 3, a drive inverter 4, a drive motor 5, a regenerative discharge resistor 6, a power converter 7, an auxiliary inverter 8, an auxiliary motor 9, a starting battery 10, a control device 11, a first voltage sensor 12, a first current sensor 13, a first rotation sensor 14, a second voltage sensor 15, a second current sensor 16, a third voltage sensor 17, a second rotation sensor 50, and a torque sensor 51. The control device 11 receives the operating amount Racc of the accelerator 53, which is an operating device for the drive motor 5, as input.

[0061] Figure 14 is a block diagram showing the processing of the DC voltage command correction unit 24 in this embodiment. In Figure 14, the state quantity calculation unit 24a calculates the state quantity KR based on the operating amount Racc of the accelerator 53. The main engine side DC voltage VmDC fluctuates according to the load's power requirements, and one factor causing the load's power requirements to fluctuate is the operator's operation of the accelerator 53. Therefore, in this embodiment, the change in the accelerator operating amount ΔRacc per unit time Δt is calculated as the state quantity KR, which changes according to the fluctuations in the load's power requirements (Equation 4).

[0062]

number

[0063] In the method for calculating the state variable KR using Equation 4, if the change in accelerator operation amount ΔRacc per unit time Δt increases in the positive direction, the state variable KR increases, and if the change in accelerator operation amount ΔRacc per unit time Δt increases in the negative direction, the state variable KR decreases. The larger the state variable KR, the greater the fluctuation of the main engine-side DC voltage command value VmDC*, and transient fluctuations of the main engine-side DC voltage VmDC can be detected in advance from the state variable KR. After calculating the state variable KR, the correction value ΔVmDC* of the main engine-side DC voltage command value VmDC* is calculated according to the map characteristics of Figure 10(a) or Figure 10(b), and the correction value ΔVaDC* of the auxiliary engine-side DC voltage command value VaDC* is calculated according to the map characteristics of Figure 10(c), similar to the first embodiment. Next, the correction value ΔVmDC* is added to the main engine DC voltage command value VmDC*, and the correction value ΔVaDC* is added to the auxiliary engine DC voltage command value VaDC*. This suppresses fluctuations in the main engine DC voltage VmDC and the auxiliary engine DC voltage VaDC.

[0064] (summary) In this embodiment, the electric drive system includes an operating device 53 that specifies the required torque for the travel motor 5, and the control device 11 calculates a state variable KR based on the operating amount Racc of the operating device 53.

[0065] In this embodiment configured as described above, as in the first embodiment, it is possible to suppress fluctuations in the main winding DC voltage VmDC and the auxiliary winding DC voltage VaDC of the two-winding induction generator 2 with a single power converter 7. [Examples]

[0066] A third embodiment of the present invention will be described, focusing on the differences from the first embodiment.

[0067] Figure 15 is a block diagram showing the processing of the DC voltage command correction unit 24 in this embodiment. In Figure 15, the state quantity calculation unit 24a calculates the amount of fluctuation of the main engine side DC voltage VmDC with respect to the main engine side DC voltage command value VmDC* per unit time Δt as the state quantity KR (Equation 5).

[0068]

number

[0069] In the method for calculating the state variable KR using equation 5, if the fluctuation amount of the main engine-side DC voltage VmDC per unit time Δt increases in the positive direction, the state variable KR increases, and if the fluctuation amount of the main engine-side DC voltage VmDC per unit time Δt increases in the negative direction, the state variable KR decreases. After calculating the state variable KR, similar to the first embodiment, the correction value ΔVmDC* of the main engine-side DC voltage command value VmDC* is calculated according to the map characteristics of Figure 10(a) or Figure 10(b), and the correction value ΔVaDC* of the auxiliary engine-side DC voltage command value VaDC* is calculated according to the map characteristics of Figure 10(c). Subsequently, the correction value ΔVmDC* is added to the main engine-side DC voltage command value VmDC*, and the correction value ΔVaDC* is added to the auxiliary engine-side DC voltage command value VaDC*. This suppresses fluctuations in the main engine-side DC voltage VmDC and the auxiliary engine-side DC voltage VaDC.

[0070] (summary) In this embodiment, the power generation system 40 is equipped with a voltage sensor 17 that detects a first DC voltage VmDC, and the control device 11 calculates a state variable KR based on the deviation between the first DC voltage VmDC detected by the voltage sensor 17 and the command value VmDC* of the first DC voltage VmDC.

[0071] In this embodiment configured as described above, as in the first embodiment, fluctuations in the DC voltage on the main winding side and the DC voltage on the auxiliary winding side of the two-winding induction generator 2 can be suppressed by a single power converter 7. Furthermore, since the second rotation sensor 50 and torque sensor 51 are not required, the configuration of the power generation system 40 can be simplified.

[0072] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above and includes various modifications. For example, the embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described. Furthermore, it is possible to add parts of the configuration of one embodiment to the configuration of another embodiment, and it is also possible to delete parts of the configuration of one embodiment or replace parts of parts of another embodiment. [Explanation of Symbols]

[0073] 1… Prime mover, 2… Two-winding induction generator, 3… Rectifier, 4… Inverter for traction (load), 5… Motor for traction, 6… Regenerative discharge resistor, 7… Power converter, 8… Inverter for auxiliary equipment, 9… Motor for auxiliary equipment, 10… Starting battery, 11… Control device, 12… First voltage sensor, 13… First current sensor, 14… First rotation sensor, 15… Second voltage sensor, 16… Second current sensor, 17… Third voltage sensor, 18a, 18b, 18c… 3-phase / 2-phase conversion unit, 19… Current command calculation unit, 20… Frequency command calculation unit, 20a… Slip frequency command calculation unit, 21… Voltage command calculation unit, 22… Voltage command compensation unit, 23… Turns ratio conversion unit, 24… DC voltage command correction unit, 24a ...State quantity calculation unit, 24b...Main engine side DC voltage command correction unit, 24c...Auxiliary engine side DC voltage command correction unit, 25...2-phase / 3-phase conversion unit, 26...Control signal generation unit, 30...Vehicle body, 31...Cargo bed, 32...Driver's seat, 33...Driven wheels, 34...Drive wheels, 40...Power generation system, 50...Second rotation sensor, 51...Torque sensor, 53...Accelerator (operating device), 210...Stator, 211...Stator core, 212...Stator slot, 213...Primary winding, 214...Wedge, 220...Rotor, 221...Rotor core, 222...Rotor slot, 223...Secondary conductor, 2131...Main winding, 2132...Auxiliary winding, 2231...Rotor bar, 2232...End ring, 230...Gap.

Claims

1. A generator having a stator including a main winding and an auxiliary winding, A rectifier connected to the main winding, which converts the AC voltage generated by the main winding into a first DC voltage, A power converter connected to the auxiliary winding controls the voltages of the main winding and the auxiliary winding, and converts the AC voltage generated by the auxiliary winding into a second DC voltage, In a power generation system comprising a control device that controls the power converter according to a command value for the first DC voltage and a command value for the second DC voltage, The control device is The value per unit time of the amount of change that changes in response to fluctuations in the power demand of the load connected to the rectifier or the power converter is calculated as a state variable. Based on the aforementioned state variables, a first voltage correction value is calculated to compensate for the fluctuation of the first DC voltage due to fluctuations in the power demanded by the load, and a second voltage correction value is calculated to compensate for the fluctuation of the second DC voltage due to fluctuations in the power demanded by the load. A control signal is generated based on the value obtained by adding the first voltage correction value to the command value of the first DC voltage, and the value obtained by adding the second voltage correction value to the command value of the second DC voltage. The power converter is controlled by the aforementioned control signal. A power generation system characterized by the following features.

2. In the power generation system according to claim 1, The system includes a voltage sensor that detects the first DC voltage, The control device calculates the value per unit time of the deviation between the first DC voltage detected by the voltage sensor and the command value of the first DC voltage as the state variable. A power generation system characterized by the following features.

3. The power generation system according to claim 1, The driving motor and The system includes a load connected to the rectifier, and a drive inverter that converts the first DC voltage into an AC voltage and supplies it to the drive motor. An electric drive system characterized by the following:

4. In the electric drive system according to claim 3, The control device calculates the value per unit time of the product of the torque and rotational speed of the drive motor as the state variable. An electric drive system characterized by the following:

5. In the electric drive system according to claim 3, The vehicle is equipped with an operating device that specifies the required torque for the aforementioned drive motor, The control device calculates the value per unit time of the operating amount of the operating device as the state variable. An electric drive system characterized by the following:

6. In the electric drive system according to Claim 1, The control device calculates the first voltage correction value as positive and the second voltage correction value as negative when the state variable is positive, and calculates the first voltage correction value as zero or negative and the second voltage correction value as positive when the state variable is negative. An electric drive system characterized by the following:

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