Three-phase inverter device

Abstract

To provide a three-phase inverter INV device which does not require a large element size as an additional element from a two-level INV and can also achieve a high motor loss reduction effect.SOLUTION: Coil short switches 7a to 7c are connected in parallel with coils 5a to 5c. Based on operations of the coil short switches 7a to 7c, a three-phase inverter device can be switched between and function as T-NPC system 3 level INV and ARCP system software SW-INV.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a three-phase inverter (hereinafter referred to as INV) device used to control a three-phase motor provided in an electric vehicle. [Background technology]

[0002] Conventionally, two-level INVs have been used in three-phase INV devices for electric vehicle main engines. Two-level INVs have a series-connected circuit of upper and lower arm semiconductor switching elements for three phases (U, V, and W), with the connection point between the upper and lower arms of each phase connected to each phase of the three-phase motor. By adopting SiC elements for the semiconductor switching elements of such two-level INVs, it is becoming possible to reduce the proportion of INV loss in the entire vehicle. However, to further improve power efficiency, that is, to extend the driving range and reduce battery capacity, it is necessary to reduce motor loss.

[0003] Effective means of reducing motor loss are (1) multi-level operation and (2) high carrier frequency.

[0004] (1) When considering the trade-off between loss reduction and cost increase, three levels are optimal for multi-level INVs. An example of a three-level INV is the T-NPC type three-level INV.

[0005] The T-NPC three-level INV divides the power supply voltage VH in half using two smoothing capacitors connected in series between the power line and ground (GND) line to form a potential of VH / 2. Intermediate elements that can control the on / off of current in both directions are provided between the upper and lower arms of each phase and between each phase of the motor. This T-NPC three-level INV can reduce current ripple by half by outputting three levels: VH, VH / 2, and GND. This makes it possible to reduce the motor's iron loss (here, hysteresis loss and eddy current loss) as well as the INV's switching (hereafter referred to as SW) loss.

[0006] (2) Increasing the carrier frequency in a two-level INV, for example, from 10 kHz to 100 kHz, increases the SW loss associated with this, and therefore requires the application of soft SW technology to reduce this. For example, an INV to which soft SW technology is applied is the DC link type soft SW-INV shown in Patent Document 1, and an INV to which soft SW technology suitable for main engine INVs is applied is the two-level ARCP type soft SW-INV.

[0007] Like the T-NPC 3-level invertor, the ARCP soft SW-INV is equipped with a smoothing capacitor. Additionally, it includes the above-mentioned intermediate element as an auxiliary element, a coil connected in series with it, and an auxiliary resonant circuit with a capacitor connected in parallel to the semiconductor switching element of each arm. The ARCP soft SW-INV doubles the carrier signal frequency, reducing current ripple by half, just like the multi-level 3-level invertor, and reducing motor iron loss (hysteresis loss in this case). The higher the carrier signal frequency, the more the current ripple can be reduced, allowing the motor drive current to approach an ideal sinusoidal waveform. However, the INV's SW loss will increase or decrease depending on the reduction in one carrier cycle due to the soft SW and the increase in the number of cycles due to the higher frequency. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Patent Publication No. 2017-122390 Summary of the Invention [Problem to be solved by the invention]

[0009] In a T-NPC type 3-level INV, the intermediate element added to a 2-level INV only needs to withstand a voltage of about VH / 2+α, which takes into account VH / 2 plus +α for surges. However, when the INV is running, the intermediate element is constantly switched on and energized, just like the semiconductor switching elements in the upper and lower arms of the main circuit, so the intermediate element also needs to be of the same size as the semiconductor switching elements in the main circuit. This creates a tradeoff in that it increases the cost of the INV.

[0010] On the other hand, in the ARCP type soft SW-INV with a higher carrier frequency, only a short pulse of resonant current of, for example, 1 μs or less flows through the auxiliary resonant circuit when the main circuit element is on. For this reason, the auxiliary element added only needs to have a similar withstand voltage of about VH / 2+α, and can be a small chip element size that satisfies the pulse rating. Because the element size can be reduced, the cost increase can be smaller compared to the T-NPC type 3-level INV, even when including the coil and capacitor that make up the auxiliary resonant circuit. However, the T-NPC type 3-level INV is more effective in reducing motor loss.

[0011] As described above, the T-NPC type 3-level INV requires a large element size, which increases the cost of the INV, but the ARCP type soft SW-INV, which uses a higher carrier frequency, requires a small element size, but is less effective in reducing motor loss.

[0012] An object of the present disclosure is to provide a three-phase INV device that does not require a large element size and can also achieve a high motor loss reduction effect in a range that is effective in improving power consumption. [Means for solving the problem]

[0013] One aspect of the present disclosure is a method for manufacturing a semiconductor device comprising: A three-phase INV device that drives a three-phase motor (MG) in an electric vehicle with three-phase AC based on current supplied from a DC power source (1), It is possible to control switching between conventional 2-level INV, T-NPC type 3-level INV, and 2-level ARCP type soft SW-INV.

[0014] In this way, it is possible to switch between the conventional 2-level INV, the T-NPC 3-level INV, and the ARCP soft SW-INV. By switching to the T-NPC 3-level INV, it is possible to further reduce the INV SW loss in addition to the motor iron loss, while allowing the elements added from the conventional 2-level INV to have a small chip size like the ARCP soft SW-INV. Therefore, it is possible to create a three-phase INV device that does not require a large element size and can achieve a high motor loss reduction effect.

[0015] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0016] [Figure 1] This is a circuit diagram of a conventional two-level INV. [Figure 2] This is a circuit diagram of a T-NPC type 3-level INV. [Figure 3A] 1 is an explanatory diagram of the relationship between the reference sine wave S of a three-phase AC waveform, triangular wave-shaped carrier signals S1 and S2, and the duty ratio of each element, and the on / off operation of each element. [Figure 3B] 1 is an explanatory diagram of the relationship between the reference sine wave S of a three-phase AC waveform, triangular wave-shaped carrier signals S1 and S2, and the duty ratio of each element, and the on / off operation of each element. [Figure 3C] 1 is an explanatory diagram of the relationship between the reference sine wave S of a three-phase AC waveform, triangular wave-shaped carrier signals S1 and S2, and the duty ratio of each element, and the on / off operation of each element. [Figure 3D] 1 is an explanatory diagram of the relationship between the reference sine wave S of a three-phase AC waveform, triangular wave-shaped carrier signals S1 and S2, and the duty ratio of each element, and the on / off operation of each element. [Figure 4] This is a circuit diagram of the ARCP type soft SW-INV. [Figure 5] 10 is a timing chart showing the timing of turning on the semiconductor switching element of the upper arm of the ARCP type soft SW-INV. [Figure 6] 1 is a circuit diagram of a three-phase INV device according to a first embodiment of the present disclosure. [Figure 7A] FIG. 7 is an explanatory diagram of the operation of the three-phase INV device shown in FIG. [Figure 7B] FIG. 7 is an explanatory diagram of the operation of the three-phase INV device shown in FIG. [Figure 8] FIG. 10 is a diagram showing conditions for switching circuits in a three-phase INV device. [Figure 9] FIG. 10 is a circuit diagram of a three-phase INV device according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following, including other embodiments described below, identical or equivalent parts will be denoted by the same reference numerals.

[0018] (First embodiment) A three-phase INV device of this embodiment will be described. The three-phase INV device of this embodiment is used for driving a three-phase motor in an electric vehicle. This three-phase INV device is switchable between a T-NPC type three-level INV, an ARCP type soft SW-INV, and a conventional two-level INV that has been commonly used in the past. Therefore, before describing the specific configuration of the three-phase INV device of this embodiment, the conventional two-level INV, the T-NPC type three-level INV, and the ARCP type soft SW-INV will first be described.

[0019] As shown in Figure 1, a conventional two-level INV has a smoothing capacitor 2 connected in parallel to a DC power supply 1, and has series-connected circuits of upper-arm and lower-arm semiconductor switching elements 3a-3f for three phases: U, V, and W. The connection point between the upper and lower arms is connected to each phase of a three-phase motor MG. By sequentially turning on and off the upper-arm and lower-arm semiconductor switching elements 3a-3f in corresponding combinations for each of the U, V, and W phases, a typical sinusoidal wave energization supplies each phase of the three-phase motor MG with a sinusoidal waveform drive current shifted by 120° out of phase. This drives the three-phase motor MG with three-phase AC.

[0020] In contrast, as shown in Figure 2, the T-NPC three-level INV uses two series-connected capacitors 2a and 2b connected in parallel to a DC power supply 1 as smoothing capacitor 2, dividing the power supply voltage VH in half to form a potential of VH / 2. Hereinafter, the connection point between capacitors 2a and 2b, i.e., the point where the potential of VH / 2 is formed, will be referred to as the midpoint potential point. Also, series-connected circuits of upper-arm and lower-arm semiconductor switching elements 3a to 3f are provided for three phases: U phase, V phase, and W phase. In addition, intermediate elements 4a to 4c are provided between the upper and lower arms of each phase and the midpoint potential point.

[0021] The intermediate elements 4a-4c are composed of pairs of elements 4aa, 4ab, 4ba, 4bb, 4ca, and 4cb, each consisting of a common-source back-to-back connected N-channel MOSFET. When one of the elements 4aa, 4ba, or 4ca, located on the right side of the drawing, is turned on, current flows from the three-phase motor MG to the midpoint. When the other elements 4ab, 4bb, or 4cb, located on the left side of the drawing, are turned on, current flows from the midpoint to the three-phase motor MG. Therefore, bidirectional current flow is possible based on the operation of the intermediate elements 4a-4c. By linking this bidirectional current flow with the operation of the upper and lower arm semiconductor switching elements 3a-3f, the three-phase motor MG can be driven with three-phase AC.

[0022] Specifically, Figures 3A to 3D show the drive waveforms for one phase of a three-level INV under triangular wave comparison PWM control. The duty ratios of the semiconductor switching elements 3a to 3f and the intermediate elements 4a to 4c are set based on a three-phase AC reference sine wave S and triangular carrier signals S1 and S2. The on / off control of each element is controlled by the set duty ratio, thereby supplying a phase current equivalent to the reference sine wave S to each phase of the three-phase motor MG. For example, the semiconductor switching elements 3a and 3b of the upper and lower arms of the U-phase and the intermediate element 4a are operated as follows. The left side of each figure shows the reference sine wave S, carrier signals S1 and S2, the duty ratio of each element, and the output voltage Vout. The right side of each figure shows the on / off operation of each element at the timing indicated by the dashed lines on the left side of each figure.

[0023] First, based on the comparison of the magnitudes of the reference sine wave S, the first carrier signal S1, and the second carrier signal S2, the duty ratio of each element is set. The semiconductor switching element 3a of the upper arm turns on when S > S1, and one element 4aa of the intermediate element 4a turns on when S < S1. Also, the semiconductor switching element 3b of the lower arm turns on when S < S2, and the other element 4ab of the intermediate element 4a turns on when S > S2. That is, in the state shown in Fig. 3A, both the semiconductor switching elements 3a and 3b are off, and both one element 4aa and the other element 4ab of the intermediate element 4a are on. In the state shown in Fig. 3B, the semiconductor switching element 3a and the other element 4ab of the intermediate element 4a are on, and the semiconductor switching element 3b and one element 4aa of the intermediate element 4a are off. In the states of Fig. 3A and Fig. 3B described above, the motor current Iu of the U phase flows in the direction of discharging from the power supply and the intermediate potential point to the motor MG side. In the state shown in Fig. 3C, both the semiconductor switching elements 3a and 3b are off, and both one element 4aa and the other element 4ab of the intermediate element 4a are on. In the state shown in Fig. 3D, the semiconductor switching element 3a and the other element 4ab of the intermediate element 4a are off, and the semiconductor switching element 3b and one element 4aa of the intermediate element 4a are on. In the states of Fig. 3C and Fig. 3D described above, the motor current Iu of the U phase flows in the direction of sucking in from the motor MG to the intermediate potential point and GND. That is, in the T-NPC type 3-level INV, similar to the semiconductor switching elements of the upper arm and the lower arm on the main circuit side, the intermediate element is also constantly switched and energized, so an element of the same size as the semiconductor switching element of the main circuit is required for the intermediate element.

[0024] In such a T-NPC type 3-level INV, since it is possible to output three levels of VH, VH / 2, and GND, the current ripple can be reduced to 1 / 2. For this reason, in addition to the iron loss of the motor, here the hysteresis loss and eddy current loss, it is possible to reduce the SW loss of the INV.

[0025] As shown in Fig. 4, the ARCP type soft SW-INV is also provided with two capacitors 2a and 2b for dividing the circuit into two, just like the T-NPC type three-level INV. In addition, it is provided with an auxiliary resonance circuit having intermediate elements 4a to 4c of the same configuration as above as auxiliary resonance switches, coils 5a to 5c connected in series to the intermediate elements, and capacitors 6a to 6f connected in parallel to the semiconductor switching elements 3a to 3f of each arm.

[0026] Even with this ARCP-type soft SW-INV, bidirectional current can be passed by turning on one of the pair of back-to-back-connected N-channel MOSFETs that make up the intermediate elements 4a-4c. By linking this operation with the operation of the upper-arm and lower-arm semiconductor switching elements 3a-3f, it becomes possible to drive a three-phase motor MG with three-phase AC. In other words, with the ARCP-type soft SW-INV, doubling the carrier signal frequency reduces current ripple by half, similar to a multilevel, three-level system, and reduces the motor's iron loss (hysteresis loss in this case). The higher the carrier signal frequency, the more the current ripple can be reduced, allowing the drive current to approach an ideal sinusoidal waveform.

[0027] Specifically, the ARCP type soft SW-INV is equipped with an auxiliary resonant circuit and performs the following operations to enable soft SW that can handle higher frequencies. As an example, the operation at the timing when the upper arm of the W phase is to be turned on will be explained.

[0028] First, just before the upper-arm semiconductor switching element 3e is about to be turned on, the lower-arm semiconductor switching element 3f is in an on state, allowing a reflux current to flow through the lower arm. In this state, if we refer to the lower-arm terminal of the coil 5c as one end and the opposite terminal as the other end, one end of the W-phase auxiliary resonant switch 4c, element 4cb, located on the left side of the drawing, is turned on, causing one end to be at GND potential and the other end to be at the VH / 2 potential generated by capacitors 2a and 2b. Therefore, when the VH / 2 voltage is applied to the coil 5c, current flows from left to right on the drawing, and the resonant current Ir increases at a rate proportional to the inductance of the coil 5c, as shown after time ta in FIG. 5 . Then, at time tb, when the resonant current Ir supplied through the coil 5c matches the motor current Il of the three-phase motor MG, the gate voltage Vgs_Lo of the lower-arm semiconductor switching element 3f is turned low, causing it to be turned off.

[0029] As a result, the current that was circulating through the element matches the current supplied through coil 5c, and the current Ids_Lo that flows between the drain and source of semiconductor switching element 3f becomes zero. Furthermore, since the drain-source voltage Vds_Lo of semiconductor switching element 3f is also in circulating operation, it is approximately zero, at about the forward voltage Vf of the built-in diode. Since semiconductor switching element 3f is turned off in this state, it is possible to almost completely eliminate switching loss in semiconductor switching element 3f, achieving soft switching.

[0030] Next, when semiconductor switching element 3f is turned off, the resonant current Ir gradually decreases due to LC resonance between coil 5c and capacitors 6e and 6f connected in parallel to semiconductor switching elements 3e and 3f. Then, capacitor 6f is charged by the resonant current Ir, and the drain-source voltage Vds_Lo of semiconductor switching element 3f also increases. Conversely, the drain-source voltage Vds_Hi of semiconductor switching element 3e in the upper arm decreases.

[0031] Furthermore, at time tc, when the resonant current Ir matches the motor current IL of the three-phase motor MG, the gate voltage Vgs_Hi of the upper arm semiconductor switching element 3e is turned on at that timing by setting it to high level. At this time, the drain-source voltage Vds_Hi of the semiconductor switching element 3e has dropped to almost zero, and the semiconductor switching element 3e is turned on in this state, so that almost no switching loss occurs and soft switching is achieved.

[0032] Here, with the T-NPC type 3-level INV, the ability to output 3 levels reduces current ripple by half, and it is possible to reduce not only the iron loss of the motor but also the SW loss of the INV, but the large size of the intermediate elements 4a to 4c results in a significant disadvantage in terms of increased cost.On the other hand, with the ARCP type soft SW-INV, since it only needs to satisfy the pulse rating, the intermediate elements 4a to 4c can be small in size, and the element size can be small even including the coils 5a to 5c and capacitors 6a to 6c that make up the auxiliary resonant circuit, so the increase in cost is small, but the effect of reducing motor loss is lower than with the T-NPC type 3-level INV.

[0033] For this reason, the three-phase INV device 100 of this embodiment has a circuit configuration shown in FIG. 6. That is, similar to the ARCP-type soft SW-INV, two series-connected capacitors 2a, 2b are connected in parallel to a DC power source 1, and series-connected circuits of upper-arm and lower-arm semiconductor switching elements 3a-3f are provided for three phases (U, V, and W phases). The connection points between each upper arm and lower arm are connected to the corresponding phase of a three-phase motor MG. Furthermore, intermediate elements 4a-4c capable of bidirectionally passing current are provided between the upper arm and lower arm of each phase and the intermediate potential point. These intermediate elements 4a-4c have the same small chip size as the ARCP-type soft SW-INV. Furthermore, an auxiliary resonant circuit is provided, including coils 5a-5c connected in series to the intermediate elements 4a-4c, respectively, and capacitors 6a-6f connected in parallel to the semiconductor switching elements 3a-3f of each arm.

[0034] In addition, coil short switches 7a to 7c are provided in parallel with the coils 5a to 5c. The coil short switches 7a to 7c are composed of pairs of elements 7aa, 7ab, 7ba, 7bb, 7ca, and 7cb, which are N-channel MOSFETs connected back-to-back with a common source. When the coil short switches 7a to 7c are composed of semiconductor switching elements such as N-channel MOSFETs, they are made to have the same small chip element size as the intermediate elements 4a to 4c.

[0035] As shown in Fig. 7A, the coil short switches 7a-7c configured as described above allow current to flow through the coils 5a-5c when all of the elements 7aa, 7ab, 7ba, 7bb, 7ca, and 7cb are off. Then, as shown in Fig. 7B, when the coil short switches 7a-7c are turned on, the coils 5a-5c are shorted and current can flow between the three-phase motor MG and the intermediate potential point through the coil short switches 7a-7c. Therefore, based on the operation of the coil short switches 7a-7c, current can be passed through the coils 5a-5c or current can flow in both directions while the coils 5a-5c are shorted.

[0036] The three-phase INV device 100 configured in this manner can be switched to function as either the T-NPC type three-level INV or the ARCP type soft SW-INV described above based on the operation of the coil short switches 7a to 7c.

[0037] That is, by turning on the coil short switches 7a to 7c, it is possible to make it function as a T-NPC type 3-level INV that does not have the coils 5a to 5c. In this case, the operation can be the same as that of the T-NPC type 3-level INV described above. Also, by turning off the coil short switches 7a to 7c, it is possible to make it function as an ARCP type soft SW-INV that has the coils 5a to 5c. In this way, the circuit topology allows the circuit to be switched between a T-NPC type 3-level INV and an ARCP type soft SW-INV during INV operation.

[0038] When functioning as a T-NPC 3-level INV, capacitors 6a-6c are not necessary, but snubber capacitors may be connected in parallel to semiconductor switching elements 3a-3f in the INV device to suppress surges. Capacitors 6a-6c can be made to function as these snubber capacitors, so surge suppression in a T-NPC 3-level INV can also be achieved.

[0039] The timing for switching between the T-NPC 3-level INV and the ARCP soft SW-INV can be determined arbitrarily, but it is preferable to perform switching control according to the motor load of the three-phase motor MG. For example, as shown in Figure 8, in the low load range where the contribution to power consumption is high, the T-NPC 3-level INV is used to operate at a low carrier frequency. Then, in the high load range, the ARCP soft SW-INV is used to operate at a high carrier frequency that is higher than the low carrier frequency.

[0040] In this way, when operating with the T-NPC 3-level INV, the load and carrier frequency are low, so even if the intermediate elements 4a-4c and coil short switches 7a-7c are small chip size, heat generation in the elements is suppressed and they can be operated. Therefore, by operating with the T-NPC 3-level INV, the current ripple can be reduced by half, and in addition to the iron loss of the motor, the SW loss of the INV can be reduced. Furthermore, the intermediate elements 4a-4c can be made small chip size, which suppresses cost increases.

[0041] The low load region refers to a region where the load is less than 1 / 4 of the maximum load of the three-phase motor MG, and the high load region refers to a region where the load is more than 1 / 4 of the maximum load of the three-phase motor MG. The low carrier frequency is a frequency in the range of 5 to 20 kHz, for example, 10 kHz. The high carrier frequency is a frequency that is four or more times the low carrier frequency. For example, if the low carrier frequency is 10 kHz, the high carrier frequency is 40 to 100 kHz.

[0042] As described above, the three-phase invertor 100 of this embodiment can be switched between a T-NPC three-level invertor and an ARCP soft SW-inverter based on the operation of the coil short switches 7a to 7c. This allows the invertor to function as either a T-NPC three-level invertor or an ARCP soft SW-inverter, further reducing the invertor's SW loss in addition to the motor's iron loss, while still achieving a small chip size like the ARCP soft SW-inverter. Therefore, the three-phase invertor 100 can achieve a high motor loss reduction effect without requiring a large element size as an additional element from a conventional two-level invertor. Furthermore, since the coil short switches 7a to 7c are simply added as additional elements to the ARCP soft SW-inverter, it is possible to cover the entire operating range from low load to high load while suppressing cost increases.

[0043] Furthermore, the three-phase INV device 100 of this embodiment can be switched to a conventional two-level INV by turning off the intermediate elements 4a to 4c, which serve as auxiliary resonant switches. Therefore, the three-phase INV device 100 of this embodiment can be switched to use as a T-NPC type three-level INV, an ARCP type soft SW-INV, or a conventional two-level INV that has been commonly used.

[0044] (Second embodiment) The first embodiment will be described. In this embodiment, the configuration of the coil short switches 7a to 7c is changed from that of the first embodiment, but the rest is the same as in the first embodiment, so only the parts that are different from the first embodiment will be described.

[0045] As shown in Fig. 9, in the three-phase INV device 100 of this embodiment, the coil short switches 7a to 7c are configured by mechanical switches 7ac, 7bc, and 7cc instead of semiconductor switching elements. In this way, even if the coil short switches 7a to 7c are configured by mechanical switches 7ac, 7bc, and 7cc, the same effects as in the first embodiment can be obtained. In particular, this can be applied to an electric system with little load fluctuation.

[0046] (Other embodiments) Although the present disclosure has been described based on the above-described embodiment, it is not limited to the embodiment and encompasses various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0047] For example, in each of the above embodiments, an example of a circuit configuration constituting the three-phase INV device 100 is shown, but it does not necessarily have to be constituted by only the circuit elements shown in each embodiment. In other words, this does not preclude the three-phase INV device 100 from being provided with elements for realizing functions other than those described above.

[0048] In the above embodiments, the semiconductor switching elements 3a-3f, the intermediate elements 4a-4c, and the coil short switches 7a-7c provided in the main circuits constituting the upper and lower arms are configured using N-channel MOSFETs. This is also just one example, and other elements, such as IGBTs, can also be used as the semiconductor switching elements.

[0049] Furthermore, in each of the above embodiments, when numerical values ​​such as the number, values, amounts, and ranges of components of the embodiments are mentioned, they are not limited to the specific numbers, except when it is particularly clearly stated that they are essential or when they are clearly limited to a specific number in principle, etc. Furthermore, in each of the above embodiments, when the shape, positional relationship, etc. of components, etc. are mentioned, they are not limited to the shape, positional relationship, etc., except when it is particularly clearly stated or when they are clearly limited to a specific shape, positional relationship, etc. in principle, etc. [Explanation of symbols]

[0050] 1…DC power supply 2...Smoothing capacitor 2a, 2b... Capacitor 3a to 3f: Semiconductor switching elements 4a to 4c: Intermediate elements 5a~5c...Coil 6a~6f...Capacitors 7a~7c...Coil short switch

Claims

1. A three-phase inverter device that drives a three-phase motor (MG) in an electric vehicle with three-phase AC based on current supplied from a DC power source (1), A three-phase inverter device that can be switched between a conventional two-level INV, a T-NPC three-level INV, and a two-level ARCP soft SW-INV.

2. smoothing capacitors (2a, 2b) connected in parallel to the DC power supply and connected in series to form a potential obtained by dividing a power supply voltage (VH) generated by the DC power supply in half; a main circuit in which three phases of series-connected circuits of semiconductor switching elements (3a to 3f) constituting upper arms and lower arms are connected in parallel to the DC power source, and a connection point between the upper arm and the lower arm of each phase is connected to each phase of the three-phase motor; an auxiliary resonant circuit including capacitors (6a to 6f) connected in parallel to the semiconductor switching elements of the upper arm and the lower arm in each phase of the main circuit, and coils (5a to 5c) provided between the upper arm and the lower arm in each phase of the main circuit and an intermediate potential point that is a connection point of two of the smoothing capacitors and where the two divided potentials are formed; intermediate elements (4a to 4c) that are respectively disposed between the upper arm and the lower arm and between the intermediate potential point in each phase of the main circuit, are connected in series with the coil, and serve as auxiliary resonant switches that control on / off of current flow between the intermediate potential point and the three-phase motor; coil short switches (7a to 7c) connected in parallel to the coils, respectively, for switching between a state in which the coils are short-circuited and a state in which current is allowed to flow through the coils by an on / off operation, The three-phase inverter device according to claim 1, wherein switching control between the conventional two-level INV, the T-NPC type three-level INV, and the ARCP type soft SW-INV is possible based on the on / off operation of the coil short switch and the auxiliary resonant switch.

3. 3. The three-phase inverter device according to claim 2, wherein switching control between the T-NPC three-level INV and the ARCP soft SW-INV is performed according to a motor load of the three-phase motor.

4. The three-phase inverter device according to claim 3 , wherein the switching control according to the motor load is performed based on an on / off operation of the coil short switch.

5. 5. The three-phase inverter device according to claim 4, wherein when the motor load is in a low load region, the three-phase inverter device operates as the T-NPC type three-level INV at a low carrier frequency.

6. 6. The three-phase inverter device according to claim 5, wherein the low load region is when the motor load is equal to or less than 1 / 4 of the maximum motor load.

7. 6. The three-phase inverter device according to claim 5, wherein when the motor load is in a high load region, the three-phase inverter device operates as the ARCP type soft SW-INV at a high carrier frequency.

8. The three-phase inverter device according to claim 7 , wherein the high carrier frequency is four or more times higher than the low carrier frequency.

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