Drive system

Abstract

An object of the present invention is to provide a drive system comprising an induction generator having a primary winding including a main winding and an auxiliary winding, wherein the drive system is capable of supplying the power required by an auxiliary inverter even during regenerative operation, with only the auxiliary winding being energized. To achieve this, the maximum current value of the power generation converter is set based on the maximum output of the induction generator's auxiliary winding and the minimum voltage of the auxiliary winding when the traction inverter is not performing regenerative operation. The no-load current value of the induction generator is set so that the maximum current of the auxiliary winding during regenerative operation of the traction inverter does not exceed the maximum current of the power generation converter.

Description

Technical Field

[0001] The present invention relates to a drive system using an induction generator having a primary winding including a main winding and an auxiliary winding. Background Art

[0002] It is known to use a drive system having a generator with a primary winding comprising a main winding and an auxiliary winding.

[0003] For example, the generator described in Patent Document 1 is provided with a three-phase winding (equivalent to a main winding) and a dedicated excitation winding (equivalent to an auxiliary winding) separately provided therewith, the three-phase winding is connected to a battery and a drive inverter (equivalent to a driving inverter) via a diode bridge (equivalent to a rectifier), and the dedicated excitation winding is connected to a battery and a drive inverter via an excitation inverter (equivalent to a power generation converter).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 8-79908 Summary of the Invention

[0007] Patent Document 1 describes a three-phase winding (equivalent to the main winding) and a separate excitation-only winding (equivalent to the auxiliary winding). The three-phase winding is connected to a battery and a drive inverter (equivalent to the driving inverter) via a diode bridge (equivalent to a rectifier). However, there is no description of the operation of regenerating power from the drive inverter to the battery.

[0008] If the drive inverter of Patent Document 1 is supposed to regenerate power to the battery, a reverse voltage will be generated in the diode bridge. This will cause the three-phase winding to be open-circuited, and no current will be generated. Therefore, during regeneration, the three-phase winding side is not energized, and only the dedicated excitation winding side is energized.

[0009] An object of the present invention is to provide a drive system having an induction generator having a primary winding including a main winding and an auxiliary winding, wherein the drive system can supply power required by an auxiliary machine inverter even in a regenerative operation in which only the auxiliary winding side is energized.

[0010] To achieve the above-mentioned object, the drive system of the present invention comprises: an induction generator having a primary winding including a main winding and an auxiliary winding; a running inverter which supplies electric power to a running motor; an auxiliary machine inverter which supplies electric power to the auxiliary machine motor; a rectifier having an AC side terminal connected to the main winding and a DC side terminal connected to the running inverter; and a power generation converter having an AC side terminal connected to the auxiliary winding and a DC side terminal connected to the auxiliary machine inverter. In the drive system, a maximum current value of the power generation converter is set based on a maximum output of the auxiliary winding and a minimum voltage of the auxiliary winding when the running inverter is not performing a regenerative action. The no-load current value of the induction generator is set so that the maximum current of the auxiliary winding when the running inverter is performing a regenerative action does not exceed the maximum current of the power generation converter.

[0011] According to the present invention constructed as described above, the drive system includes an induction generator having a primary winding including a main winding and an auxiliary winding. By appropriately setting the maximum current value of the power generation converter and the no-load current value of the induction generator, the drive system can supply the power required by the auxiliary machine inverter from the power generation converter even during regenerative operation of the driving inverter with only the auxiliary winding side energized.

[0012] Effects of the Invention

[0013] According to the present invention, a drive system including an induction generator having a primary winding including a main winding and an auxiliary winding can supply power required by an auxiliary machine inverter even in regenerative operation in which only the auxiliary winding is energized. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This diagram shows the configuration of the drive system installed in an electric dump truck.

[0015] Figure 2 This is an explanatory diagram showing the main winding voltage and the power generation frequency of a dual-winding induction generator during various operating conditions of an electrically driven dump truck.

[0016] Figure 3 This is an explanatory diagram showing a T-type equivalent circuit on the auxiliary winding side of a two-winding induction generator during deceleration operation.

[0017] Figure 4 This is an explanatory diagram showing a simplified equivalent circuit on the auxiliary winding side of a two-winding induction generator during deceleration operation.

[0018] Figure 5 This is an explanatory diagram showing the relationship between the exciting current and the capacity required for the power generation converter.

[0019] Figure 6 This is an explanatory diagram showing the voltage and frequency when the effective value of the current on the auxiliary winding side reaches a maximum value during deceleration operation of the dual-winding induction generator.

[0020] Figure 7 This is an explanatory diagram showing the relationship between the self-inductance value and the voltage on the main winding side of a two-winding induction generator.

[0021] Figure 8 This is a diagram of the drive system installed in electric vehicles. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, identical elements are denoted by the same reference numerals, and duplicate descriptions will be omitted as appropriate.

[0023] [Example 1]

[0024] As a drive system in a first embodiment of the present invention, a drive system mounted on an electrically driven dump truck will be described.

[0025] Figure 1 It is a structural diagram of the drive system in this embodiment. Figure 1 In the example, the drive system includes a two-winding induction generator 2; a starting battery 10 for starting the two-winding induction generator 2; a traction inverter 4 for driving the traction motor 5; an auxiliary inverter 8 for driving the auxiliary motor 9; a rectifier 3; a regenerative discharge resistor 6; and a power generation converter 7. The two-winding induction generator 2 is driven by the prime mover 1. The two-winding induction generator 2 has a primary winding consisting of a main winding and an auxiliary winding, and a secondary conductor. Furthermore, the auxiliary motor 9 is, for example, a drive motor for a cooling fan that cools the regenerative discharge resistor 6 and other components.

[0026] The rectifier 3 has its AC-side terminals connected to the main winding of the two-winding induction generator 2, and its DC-side terminals connected to the driving inverter 4 and a regenerative discharge resistor 6. When the driving motor 5 is regenerative (decelerating (retarding)), the regenerative discharge resistor 6 is connected to the DC-side terminals of the rectifier 3 and the DC-side terminals of the driving inverter 4, discharging the power generated by the regenerative operation of the driving motor 5. The power generation converter 7 has its AC-side terminals connected to the auxiliary winding of the two-winding induction generator 2, and its DC-side terminals connected to the auxiliary inverter 8 and a starting battery 10. The starting battery 10 is connected to the power generation converter 7 when the two-winding induction generator 2 is started, supplying power to the power generation converter 7.

[0027] The power required by the driving inverter 4 is greater than the power required by the auxiliary inverter 8. Therefore, a converter that is more expensive than a rectifier is connected to the driving inverter 4. Figure 1As shown, by connecting it to the auxiliary machine inverter 8 that requires less electric power, the cost can be reduced.

[0028] The voltages of the main winding and auxiliary winding of the two-winding induction generator 2 are approximately proportional. Therefore, by varying the voltage of the auxiliary winding of the two-winding induction generator 2 via the power generation converter 7, the voltage of the main winding of the two-winding induction generator 2 can be controlled. If the two-winding induction generator 2 were a synchronous generator, brushes would be required to energize the field winding for voltage control. However, using an induction generator as in this embodiment eliminates the need for brushes.

[0029] During idling, when the dump truck is stopped, the mechanical output of prime mover 1 is converted primarily into AC power by the auxiliary winding of dual-winding induction generator 2. The voltage and frequency of the converted AC power are controlled by power generation converter 7. During idling, a forward voltage is generated in rectifier 3, allowing power to flow even to the main winding.

[0030] During traction operation, with the dump truck's accelerator pedal depressed, the output of prime mover 1 is converted into AC power primarily by the main winding of two-winding induction generator 2, in addition to being converted into AC power by the auxiliary winding of two-winding induction generator 2, similarly to idling operation. The voltage and frequency of the converted AC power are controlled by power generation converter 7. During traction operation, a forward voltage is generated in rectifier 3, causing power to flow to the main winding side of two-winding induction generator 2.

[0031] During deceleration, when the dump truck's brake pedal is depressed, the mechanical output of the prime mover 1 is converted into AC power by the auxiliary winding of the dual-winding induction generator 2, similarly to idling. The voltage and frequency of the converted AC power are controlled by the power generation converter 7. Furthermore, the AC power regenerated by the travel motor 5 is converted into DC power by the travel inverter 4. The voltage of the converted DC power is controlled by the travel inverter 4 so that a reverse voltage (V) is generated in the rectifier 3. G <V INV ). Therefore, during deceleration operation, the main winding side of the dual-winding induction generator 2 is not energized, and only the auxiliary winding side is energized.

[0032] The dual-winding induction generator 2 is a type of induction generator and therefore requires excitation current for its field. During deceleration, only the auxiliary winding side can be energized, so all the excitation current is generated in the auxiliary winding side, resulting in an increase in the required capacity of the power generation converter 7.

[0033] On the other hand, when a dual-winding synchronous generator is used, the magnetizing winding applied separately from the auxiliary winding is used for excitation, thereby avoiding the problem of increased capacity required for the power generation converter 7. However, the need for slip rings and brushes reduces maintainability.

[0034] When a dual-winding permanent magnet generator is used, the magnetization is performed by permanent magnets, thereby eliminating the problem of an increase in the capacity required for the power generation converter 7. However, the need for permanent magnets increases the cost.

[0035] Moreover, even in the case of a dual-winding induction generator, if there is no need to supply power to the auxiliary system as in Patent Document 1, the increase in the capacity required for the power generation converter 7 can be suppressed by simply reducing the voltage on the auxiliary winding side during deceleration operation to reduce the excitation current, thereby eliminating the problem of an increase in the capacity required for the power generation converter 7.

[0036] However, in the case of a configuration in which power is supplied to the auxiliary system as in the present embodiment, if the voltage on the auxiliary winding side is lowered during deceleration operation to reduce the excitation current, the current required to supply power to the auxiliary system, that is, the load current, will conversely increase, thereby causing the problem of increasing the capacity required by the power generation converter 7.

[0037] Under these circumstances, the problem of an increase in the capacity required for the power generation converter 7 during deceleration operation becomes a problem unique to the case where electric power needs to be supplied to the auxiliary system via the dual-winding induction generator.

[0038] If the power generation converter is placed on the main winding side and the rectifier is placed on the auxiliary winding side, if the main winding side is open during deceleration operation, the induction generator will lose control. Therefore, even during deceleration operation, operation with the main winding side open is prevented. Therefore, even when power needs to be supplied to auxiliary systems using the dual-winding induction generator, the problem of increased capacity required for the power generation converter 7 during deceleration operation does not arise.

[0039] As described above, during idling and towing operation, when the traction inverter 4 is not performing regenerative operation, power can be supplied to both the main winding and the auxiliary winding. On the other hand, during deceleration operation, when the traction motor 5 is performing regenerative operation, power is supplied only to the auxiliary winding, generating all the excitation current therein, increasing the capacity required by the power generation converter 7. In other words, using a dual-winding induction generator with low excitation current specifications can minimize the increase in capacity required by the power generation converter 7.

[0040] In this embodiment, the power generation converter 7 is configured to have a capacity capable of supplying the power required by the auxiliary machine inverter 8 during idling and traction operation. A dual-winding induction generator 2 with a small excitation current is used so that the power generation converter 7 can supply the power required by the auxiliary machine inverter 8 even during deceleration operation in which only the auxiliary winding side is energized.

[0041] The specifications of the exciting current of the dual-winding induction generator 2 are formulated below.

[0042] Figure 2 1 is an explanatory diagram showing the main winding voltage and the power generation frequency of the dual-winding induction generator 2 during various operating conditions of the electrically driven dump truck. Figure 2 In the diagram, the vertical axis is the main winding voltage and the horizontal axis is the power generation frequency.

[0043] When idling, the mechanical output of the prime mover 1 is low, which reduces the rotational speed and improves the efficiency of the prime mover 1. Since the rotational speed is low, the power generation frequency is low. When the power generation frequency is low, the voltage that can be generated is low. Let the effective value of the voltage on the main winding side of the dual-winding induction generator 2 during idling be V MainMin .

[0044] During traction operation, the mechanical output of the prime mover 1 is large, and the rotational speed, which improves the efficiency of the prime mover 1, becomes higher. The higher the rotational speed, the higher the power generation frequency. When the power generation frequency is high, the voltage that can be generated becomes higher. The effective value of the maximum voltage on the main winding side of the dual-winding induction generator 2 during traction operation is set to V MainMax , the generating frequency of the double-winding induction generator 2 during traction operation is set to f Max .

[0045] During deceleration operation, the mechanical output of the prime mover 1 is low, similar to idling operation. However, the rotational speed of the prime mover 1 is higher than during idling operation, enabling a quick switch to traction operation. Since the rotational speed is higher than during idling operation, the power generation frequency is higher. Since the power generation frequency is higher than during idling operation, the voltage that can be generated is higher. The minimum value of the power generation frequency of the dual-winding induction generator 2 during deceleration operation is set to f Min The maximum value is the same as that in traction operation, f Max .

[0046] As described above, the main winding side is energized during idling operation and traction operation, when the driving inverter 4 is not performing regenerative operation. However, since the voltage is lower during idling operation than during traction operation, the current required to supply power to the auxiliary machine inverter 8 increases, and the required capacity of the power generation converter 7 increases. In other words, as long as the power generation converter 7 has a capacity that can supply the power required by the auxiliary machine inverter 8 during idling operation, it can also supply the power required by the auxiliary machine inverter 8 during traction operation.

[0047] In addition, during deceleration operation, only the auxiliary winding side is energized. However, since the rotation speed of the prime mover 1 is higher than that during idling operation, the voltage that can be generated by the auxiliary winding side becomes higher than that during idling operation. Therefore, the current required to supply power to the auxiliary inverter 8, that is, the load current, is smaller than that during idling operation.

[0048] As a preliminary step to formulating the capacity required for the power generation converter 7 during idling operation when the driving inverter 4 is not performing regenerative operation and during deceleration operation when the driving inverter 4 is performing regenerative operation, a general formula for the converter capacity is given. If the effective value of the maximum voltage on the auxiliary winding side of the dual-winding induction generator 2 is V AuxMax , the effective value of the maximum current on the auxiliary winding side of the dual-winding induction generator 2 is set to I AuxMax , then the capacity S required by the power generation converter 7 ConvAux It can be expressed by the following formula.

[0049]

Formula 1

[0050]

[0051] If the effective turns ratio (main / auxiliary) of the main winding and the auxiliary winding of the dual-winding induction generator 2 is TR, the effective value of the maximum voltage on the auxiliary winding side of the dual-winding induction generator 2 is V AuxMax and the effective value V of the minimum voltage on the auxiliary winding side of the dual-winding induction generator 2 AuxMin It can be expressed by the following formula.

[0052]

Formula 2

[0053] V AuxMax = V MainMax / TR (Equation 2)

[0054]

Formula 3

[0055] V AuxMin = V MainMin / TR (Equation 3)

[0056] The capacity required for the power generation converter 7 during idling operation when the driving inverter 4 is not performing regenerative operation is formulated. If the maximum output of the auxiliary winding side of the dual-winding induction generator 2 is P AuxMax , the power factor of the auxiliary winding side of the dual-winding induction generator 2 is set to PF Aux , then the effective value of the maximum current on the auxiliary winding side of the dual-winding induction generator 2 during idling is I AuxMaxIdl It can be expressed by the following formula.

[0057]

Formula 4

[0058]

[0059] Because the power factor PF of the auxiliary winding side of the double-winding induction generator 2 is Aux is less than 1, so the following formula is derived.

[0060]

Formula 5

[0061]

[0062] The effective value of the minimum voltage V on the auxiliary winding side of the dual-winding induction generator 2 AuxMin = is the minimum voltage on the auxiliary winding side of the dual-winding induction generator 2 when the driving inverter 4 is not performing regenerative operation. Therefore, the maximum current value of the power generation converter 7 is based on the maximum output P on the auxiliary winding side of the dual-winding induction generator 2. AuxMax , and the minimum voltage V on the auxiliary winding side when the driving inverter 4 is not performing regenerative operation AuxMin And set.

[0063] If V AuxMax Substitute into Equation 2 and add AuxMax Substituting into equation 5, the capacity S required by the power generation converter 7 during idling is ConvAuxIdl It can be expressed by the following formula.

[0064]

Formula 6

[0065]

[0066] If V AuxMin Substituting into equation 3, the capacity S required by the power generation converter 7 during idling is ConvAuxIdl It can be expressed by the following formula.

[0067]

Formula 7

[0068] S ConvAuxIdl ≧(V MainMax / TR)×(P AuxMax / (V MainMin / TR))

[0069] ≧V MainMax ×P AuxMax / V MainMin

[0070] ≧P AuxMax ×V MainMax / V MainMin (Equation 7)

[0071] The capacity required for the power generation converter 7 during deceleration operation in which the driving inverter 4 performs a regenerative operation is formulated.

[0072] Figure 3 This is an explanatory diagram showing a T-type equivalent circuit on the auxiliary winding side of a dual-winding induction generator 2 during deceleration operation. Since the main winding side is open during deceleration operation, it is the same as a normal induction motor.

[0073] Let the primary resistance be r1, the secondary resistance be r2', the excitation reactance be xM, the primary leakage reactance be x1, the secondary leakage reactance be x2', the slip be s, and the load resistance be rL'. Furthermore, let the effective value of the voltage on the auxiliary winding side of the dual-winding induction generator 2 be V Aux , the effective value of the excitation current on the auxiliary winding side of the dual-winding induction generator 2 is set to I 0Aux , the effective value of the load current on the auxiliary winding side of the dual-winding induction generator 2 is set to I 2’Aux , the effective value of the current on the auxiliary winding side of the dual-winding induction generator 2 is set to I Aux .

[0074] Figure 4 This is an explanatory diagram for explaining a simplified equivalent circuit on the auxiliary winding side of the dual-winding induction generator 2 during deceleration operation. Figure 4 In Figure 3 The T-type equivalent circuit is simplified to such an extent that the capacity required for the power generation converter 7 can be roughly estimated. Figure 4 In the example, the power generation frequency of the dual-winding induction generator 2 is set to f, and the self-inductance value of the auxiliary winding side of the dual-winding induction generator 2 is set to L Aux .

[0075] Figure 3 In the example, the magnetizing reactance xM and the load resistance rL' are much larger than the primary resistance r1, the primary leakage reactance x1, the secondary leakage reactance x2', and the secondary resistance r2'. Figure 4 In FIG, it is simplified to show only the excitation reactance xM and the load resistance rL'.

[0076] The self-reactance X on the auxiliary winding side of the dual-winding induction generator 2 Aux It can be expressed by the following formula.

[0077]

Formula 8

[0078] X Aux =x1+xM=2πfL Aux (Equation 8)

[0079] Since the excitation reactance xM is much larger than the primary leakage reactance x1, the excitation reactance xM can be expressed as follows based on Formula 8.

[0080]

Formula 9

[0081] xM≒2πfL Aux (Equation 9)

[0082] exist Figure 4 In the simplified equivalent circuit, the primary resistor r1 and the secondary resistor r2' are omitted and there is no loss. Therefore, the output P of the auxiliary winding side of the dual-winding induction generator 2 is Aux = is equal to the power input from the load resistor rL'. Therefore, the output P of the auxiliary winding side of the dual-winding induction generator 2 is Aux It can be expressed by the following formula.

[0083]

Formula 10

[0084] P Aux = 3×I2' Aux 2 ×rL' (Equation 10)

[0085] According to Formula 10, the load resistance rL' can be expressed as follows.

[0086]

Formula 11

[0087] rL'= P Aux / (3×I2' Aux 2 ) (Formula 11)

[0088] according to Figure 4 The simple equivalent circuit of the dual-winding induction generator 2 shows the effective value of the load current I on the auxiliary winding side. 2’Aux It can be expressed by the following formula.

[0089]

Formula 12

[0090]

[0091] If the load resistance rL' in equation 12 is substituted into equation 11, the effective value of the load current on the auxiliary winding side of the dual-winding induction generator 2 is I 2’Aux It can be expressed by the following formula.

[0092]

Formula 13

[0093]

[0094] according to Figure 4 The simple equivalent circuit of the dual-winding induction generator 2 is the effective value of the excitation current I 0Aux It can be expressed by the following formula.

[0095]

Formula 14

[0096]

[0097] according to Figure 4 The simple equivalent circuit of the dual-winding induction generator 2 is the effective value of the excitation current I 0Aux In a circuit having only an inductive component, the effective value of the load current I on the auxiliary winding side of the dual-winding induction generator 2 is generated. 2’Aux The two currents are generated in a circuit having only a resistance component, so the phase difference between the two currents is 90 degrees. Therefore, the vector sum of the two currents, that is, the effective value I of the current on the auxiliary winding side of the dual-winding induction generator 2, is Aux It can be expressed by the following formula.

[0098]

Formula 15

[0099]

[0100] According to Formula 14, the effective value of the excitation current on the auxiliary winding side of the dual-winding induction generator 2 is 0Aux It can be expressed by the following formula.

[0101]

Formula 16

[0102] I 0Aux = V Aux / a (Equation 16)

[0103]

Formula 17

[0104]

[0105] According to Formula 13, the effective value of the load current I on the auxiliary winding side of the dual-winding induction generator 2 is 2’Aux It can be expressed by the following formula.

[0106]

Formula 18

[0107] I2' Aux = b / V Aux (Equation 18)

[0108]

Formula 19

[0109]

[0110] If equations 16 and 18 are substituted into equation 15, the effective value of the current on the auxiliary winding side of the dual-winding induction generator 2 is I Aux It can be expressed by the following formula.

[0111]

Formula 20

[0112]

[0113]

[0114]

Formula 21

[0115] I2 = V2 / a 2 + b 2 / V2 (Equation 21)

[0116]

Formula 22

[0117] V2=V Aux 2 (Equation 22)

[0118] In formula 20, V Aux Infinite V Aux / a is infinite, and b / V is 0 Aux is infinite, so in V Aux Between 0 and infinity I Aux There is a minimum value. When decelerating, control V Aux To make I Aux If equation 21 is differentiated by V2, it can be expressed as follows.

[0119]

Formula 23

[0120]

[0121] When Equation 23 is 0, I Aux is the minimum value, when I Aux V2 at its minimum value can be expressed by the following formula.

[0122]

Formula 24

[0123] 0=1 / a 2 -b 2 / V2 2

[0124] b 2 / V2 2 =1 / a 2

[0125] V2 2 =a 2 b 2

[0126] V2=ab (Equation 24)

[0127] If we substitute Equation 22 into V2 of Equation 24, substitute Equation 17 into a, and substitute Equation 19 into b, then when I Aux When V is at its minimum value Aux 2 and V Aux It can be expressed by the following formula.

[0128]

Formula 25

[0129]

[0130]

Formula 26

[0131]

[0132] If we substitute Equation 24 into Equation 21, then I Aux I2 at its minimum value can be expressed by the following formula.

[0133]

Formula 27

[0134] I2=ab / a 2 +b 2 / ab

[0135] =b / a+b / a

[0136] =2b / a (Equation 27)

[0137] If we substitute Equation 17 into Equation 27a and Equation 19 into Equation 27b, then when I Aux I2 at its minimum value can be expressed by the following formula.

[0138]

Formula 28

[0139]

[0140] If we substitute Equation 28 into I2 in Equation 20, then I Aux The minimum value of can be expressed by the following formula.

[0141]

Formula 29

[0142]

[0143] During deceleration operation, according to formula 29, I Aux The minimum value of the output P on the auxiliary winding side of the dual-winding induction generator 2 Aux The maximum value is obtained when the power generation frequency f of the dual-winding induction generator 2 is the maximum and the power generation frequency f of the dual-winding induction generator 2 is the minimum. AuxThe self-inductance value of the auxiliary winding side of the dual-winding induction generator 2 is set to L AuxMaxRet , the maximum output required on the auxiliary winding side of the dual-winding induction generator 2 is set to P AuxMax , then the effective value of the maximum current on the auxiliary winding side of the dual-winding induction generator 2 during deceleration operation is I AuxMaxRet It can be expressed by the following formula.

[0144]

Formula 30

[0145]

[0146] Likewise, during deceleration operation, I Aux The effective value V of the voltage on the auxiliary winding side of the dual-winding induction generator 2 when the minimum value of becomes the maximum AuxMaxRet It can be expressed by the following formula.

[0147]

Formula 31

[0148]

[0149] If V AuxMax Substitute into formula 2, and AuxMax Substituting into equation 30, the capacity S required for the power generation converter 7 during deceleration operation is ConvAuxRet It can be expressed by the following formula.

[0150]

Formula 32

[0151]

[0152] During deceleration operation I Aux The self-inductance value L on the main winding side of the dual-winding induction generator 2 when the minimum value of becomes the maximum MainMaxRet It can be expressed by the following formula.

[0153]

Formula 33

[0154] L MainMaxRet =L AuxMaxRet ×TR 2 (Equation 33)

[0155] According to formula 33, during deceleration operation, I Aux The self-inductance value L on the auxiliary winding side of the dual-winding induction generator 2 when the minimum value of becomes the maximum AuxMaxRet It can be expressed by the following formula.

[0156]

Formula 34

[0157] L AuxMaxRet =L MainMaxRet / TR 2 (Equation 34)

[0158] If L in Equation 32 AuxMaxRet Substituting into equation 34, the capacity S required for the power generation converter 7 during deceleration operation is ConvAuxRet It can be expressed by the following formula.

[0159]

Formula 35

[0160]

[0161] The self-inductance value L of the main winding side of the double-winding induction generator 2 MainMaxRet Formulated as follows, the self-inductance value L on the main winding side of the dual-winding induction generator 2 is MainMaxRet The capacity S required by the power generation converter 7 during deceleration operation expressed by equation 35 can be ConvAuxRet The capacity S required by the converter 7 for power generation during idling operation is expressed by Equation 7. ConvAuxIdl The following values.

[0162] Make S ConvAuxRet For S ConvAuxIdl The relationship between the following values can be expressed by the following formula.

[0163]

Formula 36

[0164] S ConvAuxIdl ≧S ConvAuxRet (Equation 36)

[0165] If S in formula 36 ConvAuxIdl Substitute into formula 7, and add ConvAuxRet Substituting into equation 35, the capacity S required by the power generation converter 7 during deceleration operation can be obtained. ConvAuxRet The capacity S required by the converter 7 for power generation during idling operation ConvAuxIdl The self-inductance value L on the main winding side of the dual-winding induction generator 2 is the following value: MainMaxRet It can be expressed by the following formula.

[0166]

Formula 37

[0167]

[0168] Therefore, by using the self-inductance value L on the main winding side expressed by Equation 37, MainMaxRet The double-winding induction generator of the specification can supply the power required by the auxiliary machine inverter 8 even during deceleration operation with only the auxiliary winding side energized.

[0169] The capacity S required by the power generation converter 7 during deceleration operation can be expressed by equation 35. ConvAuxRet The capacity S required by the converter 7 for power generation during idling operation is expressed by Equation 7.ConvAuxIdl The specifications of the exciting current of the dual-winding induction generator 2 are formulated as follows.

[0170] If V in Equation 14 Aux Substitute V AuxMaxRet , and substitute f into f Min , to L Aux Substitute L AuxMaxRet , then during deceleration operation I Aux The effective value I of the exciting current on the auxiliary winding side of the dual-winding induction generator 2 when the minimum value of becomes the maximum 0AuxMaxRet It can be expressed by the following formula.

[0171]

Formula 38

[0172]

[0173] The excitation current of formula 38 has the following characteristics during deceleration operation: Aux The characteristic when the minimum value of becomes the maximum.

[0174] The excitation current on the main winding side of the dual-winding induction generator 2 can be obtained from the no-load current on the main winding side when the auxiliary winding side of the dual-winding induction generator 2 is open-circuited. Since the auxiliary winding side is open-circuited, the no-load current on the main winding side can be calculated, tested, and measured as a normal induction motor having only the main winding side. This allows the excitation current on the main winding side of the dual-winding induction generator 2 to be obtained without using special methods unique to dual-winding induction generators. Typically, a no-load test is performed at the rated frequency, and thus the excitation current is measured when the power generation frequency f is the rated frequency, that is, when the power generation frequency f is during traction operation. Max The excitation current is formulated. The voltage is set to the maximum V during traction operation. MainMax .

[0175] If the power generation frequency is f Max And the voltage on the main winding side is V MainMax The self-inductance value of the main winding side of the dual-winding induction generator 2 is set to L MainMax , then the power generation frequency is f Max And the voltage on the main winding side is V MainMax The effective value of the excitation current on the main winding side is I 0MainMax It can be expressed by the following formula.

[0176]

Formula 39

[0177]

[0178] If the power generation capacity of the main winding side of the double-winding induction generator 2 is set to S Main , then the power generation frequency is f MaxAnd the voltage on the main winding side is V MainMax The effective value of the rated current of the main winding side of the double-winding induction generator 2 is I MainMax It can be expressed by the following formula.

[0179]

Formula 40

[0180]

[0181] The power generation frequency is f Max And the voltage on the main winding side is V MainMax The ratio of the excitation current on the main winding side of the dual-winding induction generator 2 to the rated current when can be expressed by the following equation by dividing equation 39 by equation 40.

[0182]

Formula 41

[0183]

[0184] The degree of magnetic saturation is at the power generation frequency f Max And the voltage on the main winding side is V MainMax When in deceleration operation I Aux The saturation coefficient K is different when the minimum value becomes the maximum value. S This is a coefficient that represents the difference in magnetic saturation between two operating states by the ratio of the self-inductance values on the main winding side, and can be expressed by the following formula.

[0185]

Formula 42

[0186] K S = L MainMaxRet / L MainMax (Equation 42)

[0187] According to formula 42, L MainMax It can be expressed by the following formula.

[0188]

Formula 43

[0189] L MainMax = L MainMaxRet / K S (Equation 43)

[0190] If L in formula 41 MainMax Substituting into Equation 43, the power generation frequency is f Max And the voltage on the main winding side is V MainMax The ratio of the excitation current on the main winding side of the dual-winding induction generator 2 to the rated current when can be expressed by the following equation.

[0191]

Formula 44

[0192]

[0193] If L in formula 44 MainMaxRet Substituting into equation 37, the capacity S required for the power generation converter 7 when decelerating is used. ConvAuxRet The capacity S required by the power generation converter 7 during idling operation ConvAuxIdl The following values are for a double-winding induction generator 2, when the power generation frequency is f Max And the voltage on the main winding side is V MainMax The ratio of the excitation current on the main winding side of the dual-winding induction generator 2 to the rated current when can be expressed by the following equation.

[0194]

Formula 45

[0195]

[0196] As described above, in this embodiment, a dual-winding induction generator 2 with low excitation current is used, allowing the power generation converter 7 to supply the power required by the auxiliary machine inverter 8 even during deceleration operation with only the auxiliary winding side energized. By using a dual-winding induction generator with an excitation current specified as expressed by Equation 45, the power generation converter 7 can supply the power required by the auxiliary machine inverter 8 even during deceleration operation with only the auxiliary winding side energized.

[0197] The capacity S required by the power generation converter 7 during idling ConvAuxIdl is the effective value V of the maximum voltage on the auxiliary winding side of the dual-winding induction generator 2 AuxMax , and the effective value I of the maximum current on the auxiliary winding side of the dual-winding induction generator 2 during idling operation AuxMaxIdl It is determined by the product of .

[0198] The capacity S required by the power generation converter 7 during deceleration operation ConvAuxRet is the effective value V of the maximum voltage on the auxiliary winding side of the dual-winding induction generator 2 AuxMax , and the effective value I of the maximum current on the auxiliary winding side of the dual-winding induction generator 2 during deceleration operation AuxMaxRet It is determined by the product of .

[0199] Thus, it is decided that S ConvAuxIdl and S ConvAuxRet The maximum voltage becomes V AuxMax That is, it can be said that the self-inductance value L on the main winding side of the dual-winding induction generator 2 is MainMaxRet , and the main winding side of the double-winding induction generator 2 at the power generation frequency f Max And the voltage on the main winding side is V MainMaxThe ratio of the excitation current to the rated current is determined by equations 37 and 45 so that the maximum current I of the auxiliary winding when the driving inverter 4 performs regenerative operation is AuxMaxRet The maximum current I of the power generation converter 7 does not exceed AuxMaxIdl .

[0200] Figure 5 1 is an explanatory diagram showing the relationship between the exciting current and the capacity required by the power generation converter 7 . Figure 5 In the figure, the horizontal axis is the excitation current I 0MainMax With rated current I MainMax The vertical axis is the capacity S required by the power generation converter 7. ConvAux The power generation capacity S of the main winding side of the double-winding induction generator 2 Main The ratio.

[0201] The capacity S required by the power generation converter 7 during idling operation is given by Equation 7. ConvAuxIdl , if its minimum value S ConvAuxIdlMin Divide by the power generation capacity S of the main winding side of the double-winding induction generator 2 Main , it can be expressed by the following formula.

[0202]

Formula 46

[0203]

[0204] As long as a double-winding induction generator with a small excitation current is used, the capacity S required by the power generation converter 7 during deceleration operation is small. ConvAuxRet The power generation capacity S of the main winding side of the double-winding induction generator 2 Main The ratio becomes S in formula 46 ConvAuxIdlMin / S Main Then, it is possible to suppress an increase in the capacity required for the power generation converter 7 .

[0205] According to equation 45, when the capacity S required for the power generation converter 7 is used to enable deceleration operation, ConvAuxRet The capacity S required by the converter 7 for power generation during idling operation ConvAuxIdl The following values are for a double-winding induction generator 2, when the power generation frequency is f Max And the voltage on the main winding side is V MainMax The maximum value I of the ratio of the excitation current on the main winding side of the double-winding induction generator 2 to the rated current when 0MainMaxMax / I MainMax It can be expressed by the following formula.

[0206]

Formula 47

[0207]

[0208] like Figure 5 As shown, the power generation frequency f is used. Max And the voltage on the main winding side is V MainMax The ratio of the excitation current of the main winding side of the double-winding induction generator 2 to the rated current is I 0MainMaxMax / I MainMax The following double-winding induction generator 2, when decelerating, requires the capacity S of the power generation converter 7 ConvAuxRet The power generation capacity S of the main winding side of the double-winding induction generator 2 Main The ratio becomes S in formula 46 ConvAuxIdlMin / S Main the following.

[0209] (Summarize)

[0210] In this embodiment, the drive system includes: an induction generator 2 having a primary winding including a main winding and an auxiliary winding; a driving inverter 4 that supplies power to a driving motor 5; an auxiliary inverter 8 that supplies power to an auxiliary motor 9; a rectifier 3 having an AC side terminal connected to the main winding and a DC side terminal connected to the driving inverter 4; and a power generation converter 7 having an AC side terminal connected to the auxiliary winding and a DC side terminal connected to the auxiliary inverter 8. In this drive system, the maximum current value I of the power generation converter 7 is AuxMaxIdl is based on the maximum output of the auxiliary winding P AuxMax , and the minimum voltage V of the auxiliary winding when the driving inverter is not performing regeneration AuxMin The no-load current value of the induction generator 2 is set so that the maximum current I of the auxiliary winding when the driving inverter 4 performs regenerative operation is AuxMaxRet The maximum current of the power generation converter 7 is not exceeded.

[0211] According to this embodiment configured as described above, the drive system includes an induction generator 2 having a primary winding including a main winding and an auxiliary winding. By appropriately setting the maximum current value of the power generation converter 7 and the no-load current value of the induction generator 2, the drive system can supply the power required by the auxiliary machine inverter 8 from the power generation converter 7 even during regenerative operation of the driving inverter 4 with only the auxiliary winding side energized.

[0212] In addition, in this embodiment, the maximum voltage of the main winding of the induction generator 2 is set to V MainMax , set the minimum voltage of the main winding to V MainMin The maximum frequency of the induction generator 2 when the driving inverter 4 performs regenerative operation is set to f Max The minimum frequency of the induction generator 2 when the driving inverter 4 performs regenerative operation is set to f Min, the power generation capacity of the main winding is set to S Main , the maximum output of the auxiliary winding is set to P AuxMax , set the saturation coefficient to K S In the case of , the ratio of the excitation current of the main winding to the rated current is as follows: wherein the saturation coefficient is the current I of the auxiliary winding during the regenerative operation of the driving inverter 4. AUX The self-inductance value of the main winding when the minimum value becomes the maximum is relative to the power generation frequency of the induction generator 2. Max And the voltage on the main winding side is V MainMax The ratio of the self-inductance values of the main windings is:

[0213]

Formula 48

[0214]

[0215] As a result, the upper limit of the exciting current of the induction generator 2 is set, and thus it is possible to suppress an increase in the capacity required for the power generation converter 7 .

[0216] [Example 2]

[0217] The second embodiment of the present invention will be described focusing on the differences from the first embodiment.

[0218] The degree of magnetic saturation is at the power generation frequency f Max And the voltage on the main winding side is V MainMax When in deceleration operation I Aux In formula 42, the ratio of the self-inductance value on the main winding side, that is, the saturation coefficient K S To express the difference in magnetic saturation between these two operating states.

[0219] If based on Figure 3 and Figure 4 Considering the self-inductance value L of the induction motor by the equivalent circuit of , it can be calculated based on the ratio of the voltage V and the current I during no-load operation with the slip rate s set to 0, and can be expressed by the following formula.

[0220]

Formula 49

[0221]

[0222] In order to calculate the deceleration operation I Aux When the minimum value of L becomes the maximum AuxMaxRet , it is necessary to use formula 31 to calculate I during deceleration operation Aux The voltage V when the minimum value becomes the maximum AuxMaxRet That is, in order to obtain the saturation coefficient K SThe value of , and the following issues arise: need to calculate the deceleration operation I Aux The voltage V when the minimum value becomes the maximum AuxMaxRet .

[0223] Figure 6 It indicates the effective value of the current on the auxiliary winding side during deceleration operation. Aux Graph illustrating the voltage and frequency of the dual-winding induction generator 2 when the minimum value of becomes the maximum. Figure 6 In the figure, the horizontal axis is the power generation frequency f and f Max The vertical axis is the effective value V of the voltage on the main winding side of the dual-winding induction generator 2. Main With V MainMax The ratio.

[0224] The magnetic flux density that determines the degree of magnetic saturation is proportional to the voltage / frequency. The power generation frequency is f Max And the voltage on the main winding side is V MainMax The voltage / frequency is 1, in contrast, during deceleration operation, I Aux The voltage / frequency when the minimum value becomes the maximum is V / f. At this time, the magnetic flux density of the latter is as follows: Figure 6 The shown value is V / f times of the former, which is lower than the former.

[0225] Figure 7 1 is an explanatory diagram showing the relationship between the self-inductance value and the voltage on the main winding side of the dual-winding induction generator 2 . Figure 7 The horizontal axis is the effective value of the voltage on the main winding side V Main The maximum effective value of the voltage on the main winding side is V MainMax The vertical axis is the self-inductance value L when not saturated. Main－Unsaturated The self-inductance value L on the main winding side Main The ratio of the power generation frequency is f Max situation.

[0226] In the experiment of L based on formula 48, the minimum value of L when V is reduced within the experimental range is the self-inductance value L when it is not saturated. Main－Unsaturated .

[0227] according to Figure 7 , in deceleration operation I Aux The self-inductance value L when the minimum value becomes the maximum Main Almost equal to the unsaturated self-inductance value L Main－Unsaturated Therefore, even if you do not know the deceleration operation Aux The voltage V when the minimum value becomes the maximum AuxMaxRet , the self-inductance value L when not saturated can also be calculated through experiments Main－Unsaturated , the saturation coefficient K of formula 42 S It can be expressed by the following formula.

[0228]

Formula 50

[0229] K S = L Main－Unsaturated / L MainMax (Equation 49)

[0230] Therefore, by calculating L in equation 48 based on the relationship between voltage and current obtained by a normal test called a no-load test of an induction motor, the power generation frequency f expressed by equation 49 can be obtained. Max And the voltage on the main winding side is V MainMax Saturation coefficient K S .

[0231] (Summarize)

[0232] The saturation coefficient K in this embodiment S It is set based on the relationship between voltage and current obtained through a no-load test of the induction generator 2 .

[0233] According to the present embodiment constructed as described above, the saturation factor KS is set based on the relationship between the voltage and current obtained in a no-load test of the induction generator 2. This allows the excitation current on the main winding side of the two-winding induction generator 2 to be obtained without using special methods unique to two-winding induction generators.

[0234] [Example 3]

[0235] The third embodiment of the present invention will be described focusing on the differences from the first embodiment.

[0236] If L in formula 43 MainMaxRet Substituting into Equation 37, the generating frequency is f Max And the voltage on the main winding side is V MainMax The self-inductance value L of the main winding side of the dual-winding induction generator 2 is MainMax It can be expressed by the following formula.

[0237]

Formula 51

[0238] L MainMax ≧V MainMin 2 / (πK S f Min P AuxMax )(Formula 50)

[0239] Since the saturation coefficient K obtained by Equation 42 and Equation 49 S It will not be less than 1, so the power generation frequency is f Max And the voltage on the main winding side is V MainMaxThe self-inductance value L of the main winding side of the dual-winding induction generator 2 is MainMax The range of can be expressed by the following formula.

[0240]

Formula 52

[0241]

[0242] If the number of turns of the main winding of the double-winding induction generator 2 is increased, the power generation frequency is f Max And the voltage on the main winding side is V MainMax The self-inductance value L of the main winding side of the dual-winding induction generator 2 is MainMax However, increasing the number of turns requires reducing the cross-sectional area of the winding or increasing the total length of the winding, which increases the resistance of the winding and increases the copper loss of the two-winding induction generator 2. Increased copper loss reduces the efficiency of the two-winding induction generator 2 or increases the temperature of the two-winding induction generator 2. As a result, to suppress the decrease in efficiency and the increase in temperature, the size of the two-winding induction generator 2 must be increased, or expensive materials must be used for the two-winding induction generator 2.

[0243] Although the power generation frequency can be made f by reducing the gap between the stator and the rotor of the double-winding induction generator 2 Max And the voltage on the main winding side is V MainMax The self-inductance value L of the main winding side of the dual-winding induction generator 2 is MainMax However, reducing the gap may sometimes cause increased vibration and noise in a two-winding induction generator.

[0244] The self-inductance value L is specified by formula 51 MainMax By setting the upper limit of , it is possible to prevent the double-winding induction generator 2 from being required to have an excessively high inductance specification.

[0245] (Summarize)

[0246] In this embodiment, the power generation frequency of the induction generator 2 is f Max And the voltage of the main winding is V MainMax The self-inductance value of the main winding is L MainMax It is smaller than the value of the following formula 53 and larger than the value of the following formula 54.

[0247]

Formula 53

[0248]

[0249]

Formula 54

[0250]

[0251] According to the present embodiment constructed as above, by specifying the self-inductance value LMainMax The upper limit of can prevent the induction generator 2 from being required to have excessively high inductance specifications.

[0252] [Example 4]

[0253] As the drive system in the fourth embodiment of the present invention, a drive system mounted on an electric vehicle as an electrically driven vehicle has been described.

[0254] Figure 8 It is a structural diagram of the drive system in this embodiment. Figure 8 In the first embodiment ( Figure 1 The difference between the first embodiment and the second embodiment (shown in FIG. 1 ) lies in the connection method of the starting battery 10A. While the starting battery 10 of the first embodiment is connected to the DC side terminals of the power generation converter 7 and the DC side terminals of the auxiliary machine inverter 8 only when the dual-winding induction generator 2 is started, the starting battery 10A of this embodiment is always connected to the DC side terminals of the power generation converter 7 and the DC side terminals of the auxiliary machine inverter 8.

[0255] The auxiliary systems of electric vehicles are generally 12-42V systems. A battery with the same voltage as the auxiliary systems is mounted on the vehicle body. Using this battery as a starting battery 10' ensures that the starting battery 10' has the same voltage as the auxiliary systems, allowing the starting battery 10' to be constantly connected to the power generation converter 7 and the auxiliary inverter 8.

[0256] (Summarize)

[0257] According to the present embodiment configured as described above, in the drive system mounted on the electric vehicle, similarly to the first embodiment, the power required by the auxiliary machine inverter 8 can be supplied even in the regenerative operation in which only the auxiliary winding side is energized.

[0258] Furthermore, this embodiment includes a starting battery 10A that is constantly connected to the DC-side terminals of the power generation converter 7 and the DC-side terminals of the auxiliary inverter 8. The voltage of the starting battery 10A is the same as the voltage of the DC-side terminals of the auxiliary inverter 8. This eliminates the need to switch the connection of the starting battery 10A, reducing the cost and electrical loss of switching components. Furthermore, the starting battery 10A can be charged while the dual-winding induction generator 2 supplies power to the auxiliary inverter 8.

[0259] While the embodiments of the present invention have been described in detail above, the present invention is not limited to the aforementioned embodiments and encompasses various variations. For example, the aforementioned embodiments have been described in detail to facilitate understanding of the present invention, but are not necessarily limited to all of the described configurations. Furthermore, portions of the configurations of one embodiment may be added to the configurations of another embodiment, or portions of the configurations of one embodiment may be deleted or replaced with portions of another embodiment.

[0260] Description of Reference Numerals

[0261] 1…Prime mover, 2…Dual-winding induction generator, 3…Rectifier, 4…Travel inverter, 5…Travel motor, 6…Regenerative discharge resistor, 7…Generation converter, 8…Auxiliary inverter, 9…Auxiliary motor, 10, 10A…Starting battery.

Claims

1. A drive system comprising: an induction generator having a primary winding including a main winding and an auxiliary winding; a driving inverter that supplies electric power to the driving motor; an auxiliary machine inverter that supplies power to the auxiliary machine motor; a rectifier having an AC side terminal connected to the main winding and a DC side terminal connected to the driving inverter; and A power generation converter, having an AC side terminal connected to the auxiliary winding and a DC side terminal connected to the auxiliary machine inverter, The drive system is characterized in that The maximum current value of the power generation converter is set based on the maximum output of the auxiliary winding and the minimum voltage of the auxiliary winding when the driving inverter is not performing a regenerative operation. The no-load current value of the induction generator is set so that the maximum current of the auxiliary winding during the regenerative operation of the driving inverter does not exceed the maximum current of the power generation converter.

2. The drive system according to claim 1, characterized in that The maximum voltage of the main winding is set to V MainMax , The minimum voltage of the main winding is set to V MainMin , The maximum frequency of the induction generator when the driving inverter performs regenerative operation is f Max , The minimum frequency of the induction generator when the driving inverter performs regenerative operation is f Min , The power generation capacity of the main winding is set as S Main , The maximum output of the auxiliary winding is set to P AuxMax , Set the saturation coefficient to K S The saturation coefficient is the self-inductance of the main winding when the current of the auxiliary winding becomes maximum during the regenerative operation of the driving inverter relative to the power generation frequency of the induction generator. Max And the voltage of the main winding is V MainMax The ratio of the self-inductance of the main winding, In the above case, the ratio of the excitation current of the main winding to the rated current is equal to the following formula 1, which is 3. The drive system according to claim 2, characterized in that: The power generation frequency of the induction generator is f Max And the voltage of the main winding is V MainMax The self-inductance value of the main winding at the time is smaller than the value of the following formula 2 and larger than the value of the following formula 3, The formula 2 is The formula 3 is 4. The drive system according to claim 2, characterized in that: The saturation coefficient is set based on a relationship between voltage and current obtained through a no-load test of the induction generator.

5. An electrically driven dump truck, characterized in that: The drive system according to claim 1 is mounted.

6. An electrically driven vehicle, characterized in that: The drive system according to claim 1 is mounted.

7. The electrically driven vehicle according to claim 6, wherein: a starting battery that is constantly connected to the DC side terminals of the power generation converter and the DC side terminals of the auxiliary machine inverter; The voltage of the starting battery is the same as the voltage of the DC side terminal of the auxiliary machine inverter.

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