Inverter device and vehicle electric compressor having the same

Abstract

The present application aims to provide an inverter device capable of reliably protecting a power semiconductor element and further capable of achieving an optimum operation considering a withstand voltage. The inverter device has a junction temperature estimation calculation section (32) that estimates a junction temperature Tj by adding a temperature rise value ΔT based on a loss P of the power semiconductor element (16U-17W) to a temperature Tth detected by a temperature sensor (22), and corrects in a direction in which an influence of heat generation of other electronic components and a wiring pattern of a control substrate (11) other than the power semiconductor element (16U-17W) on the temperature sensor (22) is excluded when the junction temperature Tj is estimated.

Description

Technical Field

[0001] The present invention relates to, for example, an inverter device for operating an electric motor of an electric compressor and an electric compressor for a vehicle equipped with the inverter device. Background Technology

[0002] In recent years, hybrid vehicles and electric vehicles have received much attention due to environmental concerns. However, in the air conditioning systems of such hybrid vehicles, electric compressors are used as refrigerant compressors. These electric compressors are driven by an electric motor powered by the vehicle's battery (power source), and the electric motor operates through an inverter device.

[0003] This type of inverter device controls the energization of each phase of the motor by switching power semiconductor elements (such as IGBTs or MOSFETs) in a bridge structure. However, the losses of these power semiconductor elements generate heat. Therefore, especially in the case of electric compressors used in vehicles with electric compressors in harsh temperature (high temperature) environments such as engine compartments, overheat protection of the power semiconductor elements constituting the inverter device becomes extremely important.

[0004] As a protection method that takes into account the heat generation of the power semiconductor element mentioned above, there is a protection method that estimates the junction temperature of the power semiconductor element and stops operation based on the condition that the junction temperature has risen to a predetermined value. The junction temperature refers to the chip temperature inside the power semiconductor element (the surface temperature of the IGBT chip or MOSFET chip and FWD chip), which is detected by a temperature sensor (temperature detector) at the temperature of the control board (the temperature near the power semiconductor element) connected to the terminal of the power semiconductor element. The temperature rise value is obtained by adding a temperature rise value equivalent to the heat generated by the losses consisting of the switching losses and steady-state losses (conduction losses or current carrying losses) of the power semiconductor element to the detected value (for example, see Patent Document 1 and Patent Document 2).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-46647

[0008] Patent Document 2: Japanese Patent No. 6330219

[0009] Patent Document 3: Japanese Patent No. 3983439 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] However, on the control board equipped with the temperature detector, there are other electronic components or wiring patterns besides the power semiconductor elements, which also generate heat when powered on. Since this heat is transferred to the temperature detector, there is a problem that the temperature detector may detect a temperature higher than the actual junction temperature, thus suppressing or stopping operation when overheat protection of the power semiconductor elements is not required.

[0012] Furthermore, when the inverter device is used in the operation of the motor of the vehicle electric compressor, the power semiconductor element and the housing of the vehicle electric compressor are configured to exchange heat. This is to utilize the low-temperature intake refrigerant flowing into the housing to cool the power semiconductor element. However, the cooling effect varies depending on the motor speed. Therefore, existing methods for estimating junction temperature cannot accurately estimate the temperature, and the problem of inaccurate protection remains.

[0013] Furthermore, in the case of IGBTs, power semiconductor components are typically labeled with voltage ratings such as 600V and 1200V, and are often distributed in series with a wide range of voltage ratings. In this context, IGBTs with higher voltage ratings tend to have worse electrical characteristics and also suffer from cost disadvantages.

[0014] On the other hand, when driving the gate of the IGBT, when changing from on to off (cutoff), the inductance L of the wiring busbar, such as Figure 15 As shown on the left, a surge voltage ΔV (=L) is generated. (di / dt), but when the surge voltage ΔV exceeds the IGBT's withstand voltage (the upper limit of the allowable collector-emitter voltage), there is a risk of component damage. Therefore, for example, in the case of an electric motor driving an electric compressor mounted in a vehicle, when the upper limit voltage of the high-voltage battery has no margin relative to the withstand voltage (component withstand voltage) of the power semiconductor element, it is necessary to... Figure 15 The surge voltage ΔV shown on the left becomes extremely small. The reason for this is, as mentioned above, to avoid using the previous withstand voltage component.

[0015] On the other hand, such as Figure 15 As shown on the right, for example, the withstand voltage of an IGBT decreases as the junction temperature decreases. In this case, there is a linear decrease of several V for every 1°C decrease in junction temperature. Moreover, when the withstand voltage at a junction temperature of X°C is the upper limit voltage of a high-voltage battery plus the surge voltage ΔV, there is a possibility of damage due to withstand voltage drop during operation below X°C.

[0016] Therefore, considering the reduced withstand voltage at low temperatures and to minimize the surge voltage ΔV at cutoff, a gate resistor needs to be connected to the IGBT gate. The resistance value of this gate resistor is set to be relatively large. Through the parasitic capacitance between the gate resistor and the IGBT gate-emitter junction, the fall-off delay waveform of the signal voltage applied to the gate is reduced. However, if the resistance value of the gate resistor is increased, the current cut-off speed when the IGBT is turned off becomes slower (di / dt is smaller), such as... Figure 16 As shown, the resulting motion loss (generation loss) increases.

[0017] However, in reality, when the IGBT operates, it generates heat due to the operating losses (generating losses) mentioned above, causing the junction temperature to gradually rise, and consequently, the breakdown voltage to increase. Therefore, the initial startup at low temperatures becomes the biggest problem. However, it is necessary to handle all operating conditions, thus requiring an increase in the gate resistor value, which leads to... Figure 16 The device shown has the problem of generating significant losses, i.e., poor efficiency.

[0018] To address this issue, an optimized circuit structure that takes into account temperature-induced voltage fluctuations has been developed by varying the resistance value of the gate resistor (input resistor) according to the temperature of the power semiconductor element (see, for example, Patent Document 3). However, in this case, it is crucial to master the correct junction temperature to achieve optimal operation.

[0019] The present invention was made to solve the above-mentioned prior art problems, and its object is to provide an inverter device that can reliably protect power semiconductor elements and thus achieve optimal operation with consideration of withstand voltage, and an electric compressor for vehicles using the inverter device.

[0020] Technical means for solving technical problems

[0021] The inverter device of the first aspect of the invention is characterized by comprising: an inverter circuit having a power semiconductor element; and an inverter control unit for driving the power semiconductor element, the inverter device having a temperature detector for detecting the temperature near the power semiconductor element, the inverter control unit having a loss calculation unit for calculating the loss P of the power semiconductor element; and a junction temperature estimation calculation unit, which adds the temperature rise value ΔT obtained based on the loss P of the power semiconductor element calculated by the loss calculation unit to the temperature Tth detected by the temperature detector, and estimates the junction temperature Tj of the power semiconductor element, the junction temperature estimation calculation unit correcting for the influence of the heating of other electronic components and / or the wiring pattern of the control board on the temperature detector when estimating the junction temperature Tj, the junction temperature estimation calculation unit correcting for the influence of the heating of other electronic components and / or the wiring pattern of the control board on the temperature detector.

[0022] The inverter device of the second aspect of the invention is characterized in that, in the above invention, a temperature detector is disposed on a control board on which other electronic components are mounted.

[0023] The inverter device of the third aspect of the invention is characterized in that, in the above-mentioned inventions, the junction temperature estimation calculation unit calculates the temperature rise value ΔT by multiplying the loss P of the power semiconductor element by a predetermined thermal variable α, and changes the thermal variable α according to the operating state, and corrects in a direction that excludes the influence of the heating of the wiring pattern of other electronic components and / or the control board on the temperature detector.

[0024] The inverter device of the fourth aspect of the invention is characterized in that, in the operating state of the above invention, it includes any one of the power supply voltage, phase current, and input current, or a combination thereof, or all of them.

[0025] The inverter device of the fifth aspect of the invention is characterized in that, in the above invention, the thermal variable α is mapped to a value determined by at least two of the power supply voltage, phase current and input current.

[0026] The inverter device of the invention in aspect 6 is characterized in that, in the invention of aspect 4 or 5, the higher the power supply voltage, the greater the thermal variable α.

[0027] The inverter device of the invention in aspect 7 is characterized in that, in the invention of aspect 4 or 5, the larger the phase current, the smaller the thermal variable α.

[0028] The inverter device of the invention in aspect 8 is characterized in that, in the invention of aspect 4 or 5, the larger the input current, the smaller the thermal variable α.

[0029] The inverter device of the ninth aspect of the invention is characterized in that, in the above-mentioned inventions, the inverter control unit performs a predetermined protection action when the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit exceeds a predetermined value.

[0030] The electric compressor for vehicles of the invention of aspect 10 is characterized in that it includes an electric motor operated by the inverter device of the above-described inventions and a housing housing the electric motor, wherein the power semiconductor element and the low-temperature part of the housing are configured to exchange heat.

[0031] The electric compressor for vehicles according to aspect 11 is characterized by comprising: an inverter device including an inverter circuit having a power semiconductor element and an inverter control unit for driving the power semiconductor element; an electric motor operated by the inverter device; and a housing housing the electric motor, wherein the power semiconductor element is configured to exchange heat with the intake refrigerant via the housing, and a temperature detector for detecting the temperature near the power semiconductor element; the inverter control unit having a loss calculation unit for calculating the loss P of the power semiconductor element; and a junction temperature estimation calculation unit that estimates the junction temperature Tj of the power semiconductor element by adding the temperature Tth detected by the temperature detector to a temperature rise ΔT obtained based on the loss P of the power semiconductor element calculated by the loss calculation unit. When estimating the junction temperature Tj, the junction temperature estimation calculation unit corrects the junction temperature Tj in a direction that lowers it as the speed of the electric motor increases.

[0032] The electric compressor for vehicles according to aspect 12 is characterized in that, in the invention described above, the junction temperature estimation calculation unit calculates the temperature rise value ΔT by multiplying the power semiconductor element loss P by a predetermined heat variable α, and the higher the speed of the motor, the more the heat variable α is changed to make the heat variable α smaller.

[0033] The electric compressor for vehicles according to aspect 13 is characterized in that, in aspect 11 or 12, the inverter control unit performs a predetermined protection action when the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit exceeds a predetermined value.

[0034] The inverter device or electric compressor for vehicles according to aspect 14 is characterized in that, in the aforementioned inventions, the inverter control unit has a gate resistance changing unit that changes the resistance value of the gate resistance of the power semiconductor element, the gate resistance changing unit changing the resistance value of the gate resistance of the power semiconductor element based on the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit.

[0035] The inverter device or electric compressor for vehicles according to aspect 15 is characterized in that, in the above invention, the lower the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit in the gate resistance changing unit, the larger the resistance value of the gate resistor of the power semiconductor element; and the higher the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit, the smaller the resistance value of the gate resistor of the power semiconductor element.

[0036] The inverter device or electric compressor for vehicles of the invention of aspect 16 is characterized in that, in the invention of aspect 14 or 15, the gate resistance changing section has a variable resistor device connected to the gate of the power semiconductor element, and the resistance value of the variable resistor device is changed according to the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation section.

[0037] The inverter device or electric compressor for vehicles according to aspect 17 is characterized in that, in the above invention, the lower the junction temperature Tj of the power semiconductor element estimated by the gate resistance changing section in the junction temperature estimation calculation section, the larger the resistance value of the variable resistor device; and the higher the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation section, the smaller the resistance value of the variable resistor device.

[0038] The inverter device or electric compressor for vehicles according to aspect 18 is characterized in that, in aspect 16 or 17, the variable resistor device includes: a switch for generating a conduction signal connected to the gate of a power semiconductor element and for inputting a conduction signal to the gate; a plurality of switches for generating a disconnection signal connected to the gate of the power semiconductor element and for inputting a disconnection signal to the gate; and a plurality of resistor elements with different resistance values ​​connected to these plurality of switches for generating a disconnection signal respectively. When the power semiconductor element is disconnected, the gate resistance changing unit switches each switch for generating a disconnection signal and turns it on according to the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit, thereby changing the resistance value of the gate resistance of the power semiconductor element.

[0039] The inverter device or electric compressor for vehicles according to aspect 19 is characterized in that, in the above invention, when the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit is below a predetermined value T1, the gate resistance changing unit turns on the switch for generating a disconnection signal connected to a resistor element with a larger resistance value; when the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit is above a predetermined value T2 which is higher than the predetermined value T1, the switch for generating a disconnection signal connected to a resistor element with a smaller resistance value turns on.

[0040] Invention Effects

[0041] According to the invention of the first aspect, an inverter device includes: an inverter circuit having a power semiconductor element; and an inverter control unit for driving the power semiconductor element. The inverter device includes a temperature detector for detecting the temperature near the power semiconductor element. The inverter control unit includes a loss calculation unit for calculating the loss P of the power semiconductor element; and a junction temperature estimation calculation unit. The junction temperature estimation calculation unit adds the temperature rise value ΔT obtained based on the loss P of the power semiconductor element calculated by the loss calculation unit to the temperature Tth detected by the temperature detector, and estimates the junction temperature Tj of the power semiconductor element. When estimating the junction temperature Tj, the junction temperature estimation calculation unit corrects in a direction that excludes the influence of the heat generated by other electronic components and / or wiring patterns of the control board on the temperature detector. Therefore, especially in cases where the temperature detector is disposed on the control board as described in the second aspect, the influence of the heat generated by other electronic components or wiring patterns on the temperature detector is eliminated, and the junction temperature Tj of the power semiconductor element can be estimated more accurately.

[0042] Therefore, when performing the protection action as described in aspect 9, the usable area of ​​the power semiconductor element can be expanded, thereby reducing the component rating and achieving miniaturization and cost reduction.

[0043] Furthermore, as in the invention of the third aspect, the junction temperature estimation calculation unit calculates the temperature rise value ΔT by multiplying the power semiconductor element loss P by a predetermined thermal variable α, and changes the thermal variable α according to the operating state, thus successfully eliminating the influence of the heating of other electronic components and / or the wiring pattern of the control board on the temperature detector.

[0044] In this operating state, the power supply voltage, phase current, and input current, as in the invention of aspect 4, can be used. Moreover, as in the invention of aspect 5, by mapping the thermal variable α to a value determined by at least two of the power supply voltage, phase current, and input current, the thermal variable α can be accurately set according to the interrelated operating states.

[0045] Here, since a higher power supply voltage results in a higher junction temperature Tj for the power semiconductor element, the thermal effects from other electronic components or wiring patterns are relatively small. Therefore, as in the invention of aspect 6, by increasing the power supply voltage, the thermal variable α is increased, thereby enabling accurate estimation of the junction temperature Tj.

[0046] Furthermore, the larger the phase current, the greater the heat generated by other electronic components or wiring patterns, and the greater the heat transferred to the temperature detector. Therefore, as in the invention of aspect 7, by increasing the phase current, the thermal variable α becomes smaller, thereby enabling accurate estimation of the junction temperature Tj.

[0047] Furthermore, with a larger input current, the heat generated by the wiring pattern also increases, as does the heat transferred to the temperature detector. Therefore, as in the invention of aspect 8, by increasing the input current, the thermal variable α becomes smaller, thereby enabling accurate estimation of the junction temperature Tj.

[0048] Furthermore, in vehicle electric compressors such as those described in the 10th aspect, which are used in high-temperature environments, the inverter devices of the aforementioned inventions are used to operate the electric motor, thereby achieving highly effective overheat protection.

[0049] On the other hand, in an electric compressor for vehicles, such as the invention of aspect 11, the higher the speed of the electric motor, the higher the cooling capacity of the intake refrigerant. That is, since the junction temperature Tj of the power semiconductor element, which is provided through the heat exchange relationship between the housing and the intake refrigerant, is reduced, the junction temperature Tj is corrected in the direction of its reduction by increasing the speed of the electric motor, thereby enabling accurate estimation of the junction temperature Tj.

[0050] In this case, as in the invention of aspect 12, the junction temperature estimation calculation unit calculates the temperature rise value ΔT by multiplying the power semiconductor element loss P by a predetermined thermal variable α, and if the thermal variable α is changed so that the higher the motor speed, the smaller the thermal variable α becomes, the correct junction temperature Tj can be estimated smoothly.

[0051] Therefore, when performing protection actions as described in aspect 13, the usable area of ​​the power semiconductor element can also be expanded, thereby reducing the component rating and achieving miniaturization and cost reduction.

[0052] As described above, according to the invention of aspects 1 to 13 above, the junction temperature Tj of the power semiconductor element can be accurately estimated, and therefore, the voltage fluctuation of the power semiconductor element can be accurately controlled.

[0053] Therefore, in an inverter control unit such as that of the invention in aspect 14, a gate resistance changing unit is provided to change the resistance value of the gate resistance of the power semiconductor element. Based on the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit, the gate resistance changing unit changes the resistance value of the gate resistance of the power semiconductor element, thereby enabling optimal operation that takes into account the withstand voltage of the power semiconductor element.

[0054] For example, as with the gate resistance changing section of the invention in aspect 15, if the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation section is lower, the resistance value of the gate resistance of the power semiconductor element is larger; if the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation section is higher, the resistance value of the gate resistance of the power semiconductor element is smaller. In this case, when the junction temperature Tj is low and the withstand voltage of the power semiconductor element is reduced, the resistance value of the gate resistance can be increased and the surge voltage can be reduced; when the junction temperature Tj is high and the withstand voltage of the power semiconductor element is increased, the resistance value of the gate resistance can be reduced, thereby reducing losses.

[0055] Therefore, it is possible to avoid damage to power semiconductor components caused by surge voltage while suppressing losses and achieving efficient operation.

[0056] Specifically, for example, as in the invention of aspect 16, a variable resistor device connected to the gate of a power semiconductor element is provided in the gate resistance changing section. The resistance value of the variable resistor device is changed according to the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation section. As in the invention of aspect 17, the lower the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation section, the larger the resistance value of the variable resistor device. The higher the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation section, the more effective it is to reduce the resistance value of the variable resistor device. This enables both the prevention of damage to the power semiconductor element caused by surge voltage and the suppression of power semiconductor element generation losses.

[0057] More specifically, for example, the variable resistor device of aspect 18 includes a switch for generating a conduction signal connected to the gate of a power semiconductor element and used to input a conduction signal to the gate; a plurality of switches for generating a disconnection signal each connected to the gate of the power semiconductor element and used to input a disconnection signal to the gate; and a plurality of resistor elements with different resistance values ​​connected to these plurality of switches for generating a disconnection signal. When the gate resistance changing unit disconnects the power semiconductor element, the switches for generating a disconnection signal are switched to conduct based on the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit, thereby changing the resistance of the power semiconductor element. When the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit of the invention in aspect 19 is below a predetermined value T1, the switch for generating a disconnection signal connected to a resistor element with a larger resistance value is turned on. When the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit is above a predetermined value T2 which is higher than the predetermined value T1, the switch for generating a disconnection signal connected to a resistor element with a smaller resistance value is turned on. Thus, it is possible to prevent damage to the power semiconductor element caused by surge voltage when the power semiconductor element is disconnected and to suppress the generation loss of the power semiconductor element. Attached Figure Description

[0058] Figure 1 This is a simplified cross-sectional view of a vehicle electric compressor, which is an embodiment of the inverter device of the present invention.

[0059] Figure 2 This is a circuit diagram of an inverter device according to an embodiment of the present invention.

[0060] Figure 3 It is by Figure 2 A three-dimensional mapping diagram of the thermal variable α determined by the battery voltage and phase current held by the junction temperature estimation calculation unit of the inverter device (Example 1).

[0061] Figure 4 It is a three-dimensional mapping that illustrates the relationship between phase current and thermal variable α.

[0062] Figure 5 This is a cross-sectional view of the main parts of an electric compressor for vehicles, used to illustrate the relationship between phase current and thermal variable α.

[0063] Figure 6 It is a thermal circuit diagram used to illustrate the relationship between phase current and thermal variable α.

[0064] Figure 7 It is a three-dimensional mapping that illustrates the relationship between battery voltage (power supply voltage) and thermal variable α.

[0065] Figure 8It is a thermal circuit diagram used to illustrate the relationship between battery voltage and thermal variable α.

[0066] Figure 9 It is a graph used to illustrate the relationship between input current and thermal variable α.

[0067] Figure 10 This is a cross-sectional view of the main parts of an electric compressor for vehicles, used to illustrate the relationship between input current and thermal variable α.

[0068] Figure 11 It is a thermal circuit diagram used to illustrate the relationship between input current and thermal variable α.

[0069] Figure 12 This is a graph illustrating the relationship between the motor's rotational speed and thermal variable α (Example 2).

[0070] Figure 13 This is a cross-sectional view of the main parts of an electric compressor for vehicles, used to illustrate the relationship between the motor's rotational speed and thermal variable α.

[0071] Figure 14 It is a thermal circuit diagram used to illustrate the relationship between the speed of an electric motor and the thermal variable α.

[0072] Figure 15 This is a graph showing the relationship between the collector-emitter voltage (including surge voltage), junction temperature, and withstand voltage of the semiconductor switching element (IGBT) of the power semiconductor element in the embodiment when it is turned off.

[0073] Figure 16 This is a graph showing the relationship between the gate resistance value (gate resistance value) of the power semiconductor switching element (IGBT) of the embodiment and the surge voltage and generated losses.

[0074] Figure 17 This is a circuit diagram illustrating an example of the structure of the gate resistance changing section of the inverter device of the present invention (Example 3).

[0075] Figure 18 It means Figure 17 A diagram showing an example of the specific circuitry for the gate resistance changing section.

[0076] Figure 19 This is an explanation Figure 18 A diagram showing the operation of the gate resistance changing section. Detailed Implementation

[0077] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0078] [Example 1]

[0079] (1) Electric compressor for vehicles 1

[0080] Figure 1 This is a simplified cross-sectional view of the electric compressor 1 for vehicles to which the present invention is applied. The electric compressor 1 of this embodiment forms part of the refrigerant circuit of an air conditioning system for air conditioning the passenger compartment of a vehicle (not shown), and is mounted in the vehicle's engine compartment. The electric compressor 1 has an electric motor 3 and a scroll-type compression element 6 driven by the rotating shaft of the electric motor 3 within a metal housing 2. An inverter device 7 of the present invention is also installed within the housing 2, which operates the electric motor 3 to drive the compression element 6. Driven by the rotating shaft of the electric motor 3, the compression element 6 draws in refrigerant from the refrigerant circuit through the suction port 4, compresses it, and discharges it back into the refrigerant circuit through the discharge port (not shown).

[0081] Figure 11 shows the control board (made of resin) of the inverter device 7. Wiring patterns 34 for phase current flow and 36 for input current flow are printed on the control board 11. Additionally, Figure 16U shows a power semiconductor element constituting the inverter circuit 8 of the inverter device 7, with its terminal 37 connected to the control board 11. In this configuration, the power semiconductor element 16U (and similarly the other power semiconductor elements 16V, 16W, 17U, 17V, and 17W described later) is arranged to exchange heat with the area near the intake port 4 of the housing 2 (the low-temperature portion of the housing 2). Thus, the power semiconductor elements 16U, 16V, 16W, 17U, 17V, and 17W are arranged to exchange heat with the low-temperature intake refrigerant via the housing 2.

[0082] Additionally, 22 in the figure is a temperature sensor, which is disposed on the control board 11 and located near the power semiconductor elements 16U, 16V, 16W and 17U, 17V, 17W. Furthermore, the control board 11 also houses electronic components other than the power semiconductor elements, such as the inverter control unit 12 and the filter capacitor 9, which will be described later.

[0083] (2) Inverter device 7

[0084] then, Figure 2 This diagram shows the circuit diagram of the inverter device 7. The inverter device 7 of this embodiment includes the filter capacitor 9, wiring patterns 34 and 36, and a control board 11 connected to the inverter circuit 8, and an inverter control unit 12 composed of a microcomputer (processor). The positive DC bus 13 of the inverter circuit 8 is connected to the + terminal of the high-voltage battery (vehicle HV power supply) B mounted on the vehicle, and the negative DC bus 14 is connected to the - terminal of the high-voltage battery B. Furthermore, the filter capacitor 9 is connected between the two DC buses 13 and 14 of the inverter circuit 8. The circuit from the filter capacitor 9 to the inverter circuit 8 is called the wiring bus.

[0085] (3) Inverter circuit 8

[0086] Inverter circuit 8 changes the switching states of the multiple power semiconductor elements constituting the bridge, converting the DC power supplied from high-voltage battery B into AC power and supplying it to motor 3. Specifically, it has three power semiconductor elements 16U, 16V, and 16W constituting the upper phase of the bridge, and three power semiconductor elements 17U, 17V, and 17W constituting the lower phase of the bridge. Each power semiconductor element 16U, 16V, 16W and 17U, 17V, and 17W is a combination of semiconductor switching element 18 and a return diode 19 connected in reverse parallel with it, supplying DC power from high-voltage battery B to the DC buses 13 and 14 of inverter circuit 8.

[0087] In this inverter circuit 8, the semiconductor switching elements 18 of the upper-phase power semiconductor elements 16U, 16V, and 16W and the semiconductor switching elements 18 of the lower-phase power semiconductor elements 17U, 17V, and 17W are connected in series in a one-to-one correspondence. Hereinafter, each pair of semiconductor switching elements 18 of the power semiconductor elements 16U to 17W connected in series will be referred to as a switching arm. That is, in this embodiment, there are switching arms 21U consisting of a pair of semiconductor switching elements 18 of power semiconductor elements 16U and 17U, switching arms 21V consisting of a pair of semiconductor switching elements 18 of power semiconductor elements 16V and 17V, and switching arms 21W consisting of a pair of semiconductor switching elements 18 of power semiconductor elements 16W and 17W.

[0088] These switch arms 21U, 21V, and 21W are respectively connected between the positive DC bus 13 and the negative DC bus 14. In addition, the intermediate points MU, MV, and MW of each switch arm 21U, 21V, and 21W are nodes for outputting the phase voltages Vu, Vv, and Vw of each phase (U phase, V phase, and W phase) of the output AC, and each intermediate point MU, MV, and MW is connected to each phase of the motor 3.

[0089] In the inverter circuit 8 of this embodiment, the semiconductor switching element 18 uses an IGBT (Insulated Gate Bipolar Transistor). However, the semiconductor switching element 18 is not limited to the IGBT described herein; it could also be a MOSFET or the like. Furthermore, a temperature sensor 22 is mounted on the control board 11 near the power semiconductor elements 16U to 17W as described above. In this embodiment, the temperature sensor 22 is composed of a thermistor.

[0090] Furthermore, the DC bus 14 on the negative side of the location where the current from the motor 3 flows is connected to a shunt resistor 23, which serves as a phase current detector. If the current from the motor 3 flows through the shunt resistor 23, a potential difference is generated across the shunt resistor 23. By detecting the voltage between these two terminals, the phase currents Iu, Iv, and Iw can be calculated. Additionally, the phase current detector is not limited to the shunt resistor mentioned above; it can also be a current transformer or the like.

[0091] (4) Inverter control unit 12

[0092] On the other hand, the inverter control unit 12 includes a motor control unit 26, a PWM control unit 27, a current detection unit 28, a gate driver 29, a loss calculation unit 31, a junction temperature estimation calculation unit 32, and a temperature protection unit 33. Furthermore, the battery (HV) voltage (power supply voltage) Vb of the positive DC bus 13 is input to the PWM control unit 27 and the loss calculation unit 31.

[0093] (5) Motor control unit 26

[0094] The motor control unit 26 outputs a target waveform (modulation wave) of a three-phase sine wave applied to the motor 3 to the PWM control unit 27. The PWM control unit 27 generates a duty cycle (on-time) as a drive signal by comparing the high and low levels of the modulation wave and the carrier wave (triangular wave) output by the motor control unit 26. This duty cycle is generated for each of the U, V, and W phases and output to the gate driver 29, which drives (turns on / offs) the gates of each semiconductor switching element 18. Upon receiving the drive signal, the gate driver 29 generates signals to turn on and turn off the semiconductor switching element 18 (IGBT) based on the rising and falling edges of the drive signal. The outputs (6 outputs) of the gate driver 29 are connected to the gates of each semiconductor switching element 18 via gate resistors 39, and they are switched (turned on / off) by applying signal voltages with rising and falling edges to the gates of each semiconductor switching element 18.

[0095] Furthermore, in this embodiment, the rotational speed of the motor 3, i.e., the frequency of the phase currents Iu, Iv, and Iw, is between 400Hz and 500Hz. The period of the carrier wave in the PWM control unit 27 (hereinafter referred to as the PWM carrier period) is 20kHz, which is sufficiently small (or sufficiently short) compared to the phase currents Iu, Iv, and Iw. In addition, the thermal time constant of the power semiconductor element 16U to 17W (the time taken for the temperature rise value, as a loss component, to be transmitted to the temperature sensor 22) is approximately 50ms, and the PWM carrier period is sufficiently short (or sufficiently fast) than this thermal time constant.

[0096] The current detection unit 28 inputs the voltage across the shunt resistor 23 and calculates the phase currents Iu, Iv, and Iw based on the resistance value of the shunt resistor 23. The calculated phase currents Iu, Iv, and Iw are then input to the loss calculation unit 31.

[0097] (6) Loss Calculation Unit 31

[0098] The loss calculation unit 31 calculates the losses of each power semiconductor element 16U to 17W based on the phase currents Iu, Iv, and Iw of each phase of the U-phase, V-phase, and W-phase input from the current detection unit 28, the HV voltage (applied voltage) of the DC bus 13 on the positive side, and the duty cycle input from the PWM control unit 27. In the embodiment, the loss calculation unit 31 separately calculates the switching losses and steady-state losses (conduction losses or current-carrying losses) of the semiconductor switching elements 18 constituting each power semiconductor element 16U to 17W, as well as the switching losses and steady-state losses (conduction losses or current-carrying losses) of the return diode 19.

[0099] The switching losses and steady-state losses (conduction losses or current-carrying losses) of the semiconductor switching element 18 constitute the losses of the semiconductor switching element 18 and thus generate heat. Similarly, the switching losses and steady-state losses (conduction losses or current-carrying losses) of the return diode 19 constitute the losses of the return diode 19 and thus generate heat. These losses, in turn, constitute the losses P of each power semiconductor element 16U to 17W. The losses P of each power semiconductor element 16U to 17W calculated using the loss calculation unit 31 are input to the junction temperature estimation calculation unit 32.

[0100] In addition, in this embodiment, besides the battery voltage Vb, phase currents Iu, Iv, and Iw, information related to the input current Iin and the rotational speed NC of the motor 3 is also sent from the loss calculation unit 31 to the junction temperature estimation calculation unit 32.

[0101] (7) Junction temperature estimation calculation section 32

[0102] The junction temperature estimation calculation unit 32 calculates the estimated value of the junction temperature Tj of the semiconductor switching element 18 of each power semiconductor element 16U to 17W by adding the temperature Tth near the power semiconductor element 16U to 17W detected by the temperature sensor 22 to the temperature rise value ΔT obtained by the loss of each power semiconductor element 16U to 17W calculated by the loss calculation unit 31.

[0103] In this case, the junction temperature estimation calculation unit 32 multiplies the specified thermal variable α with the loss P of each power semiconductor element 16U to 17W calculated by the loss calculation unit 31, thereby calculating the temperature rise value ΔT. When the estimation calculation in the junction temperature estimation calculation unit 32 is expressed by formulas, it becomes the following formulas (1) and (2).

[0104] Tj = Tth + ΔT (1)

[0105] ΔT = α × P (2)

[0106] The aforementioned thermal variable α will be described in detail later. Furthermore, the calculated junction temperature Tj is input to the temperature protection unit 33.

[0107] (8) Temperature protection unit 33

[0108] The temperature protection unit 33 performs a predetermined protection action based on the junction temperature Tj of the semiconductor switching element 18 of each power semiconductor element 16U to 17W, which is estimated by the junction temperature estimation calculation unit 32. In this embodiment, the protection action is divided into two stages. First, if the highest junction temperature Tj among the junction temperatures Tj of any power semiconductor element 16U to 17W exceeds a first predetermined value TS1, the temperature protection unit 33 outputs a current limiting signal to the motor control unit 26.

[0109] Upon receiving a current limiting signal from the temperature protection unit 33, the motor control unit 26 adjusts the modulation wave to limit the current flowing through the inverter circuit 8 to a predetermined value. Furthermore, if the highest value of the junction temperature Tj exceeds a second predetermined value TS2, which is higher than the first predetermined value TS1, the temperature protection unit 33 outputs a current cut-off signal to the motor control unit 26. Upon receiving the current cut-off signal from the temperature protection unit 33, the motor control unit 26 stops the output of the modulation wave, causing all the semiconductor switching elements 18 of the power semiconductor elements 16U-17W to disconnect, thus cutting off the current flowing through the inverter circuit 8. These first predetermined values ​​TS1 and second predetermined values ​​TS2 are values ​​set based on the temperature limits of the semiconductor switching elements 18 constituting the power semiconductor elements 16U-17W.

[0110] (9) The junction temperature estimation calculation unit 32 changes the heat variable α (part 1).

[0111] Next, refer to Figures 3-8An example of controlling the thermal variable α of the above formula (2) by changing the junction temperature estimation calculation unit 32 of the inverter control unit 12 will be described. As described above, the control board 11 is equipped with electronic components other than power semiconductor elements 16U to 17W, such as wiring pattern 34 through which phase currents (Iu, Iv, Iw) flow, wiring pattern 36 through which input current Iin flow, inverter control unit 12, and filter capacitor 9.

[0112] These electronic components (12, 9) and wiring patterns (34, 36) generate heat by operating the motor 3 powered by the inverter device 7. This heat is also transferred to the temperature sensor 22, which is also mounted on the control board 11, and thus the temperature Tth detected by the temperature sensor 22 is affected and rises. Therefore, as shown in equation (1) above, if the temperature rise value ΔT, calculated based on the loss P of each power semiconductor element 16U to 17W, is directly added to the temperature Tth detected by the temperature sensor 22, the calculated junction temperature Tj is higher than the actual value, which will cause the aforementioned protection action to be performed unnecessarily in an early stage.

[0113] Therefore, as shown in Equation (2) above, the junction temperature estimation calculation unit 32 of the embodiment multiplies the loss P by a predetermined thermal variable α, and corrects the junction temperature Tj in the direction that eliminates the influence of the heating of the electronic components (12, 9) or wiring patterns (34, 36) on the temperature sensor 22 according to the operating state.

[0114] In this embodiment, the battery voltage Vb (power supply voltage) and phase currents (Iu, Iv, Iw) are used as the operating state, and the thermal variable α is determined based on these. In this embodiment, the thermal variable α is a value determined by the battery voltage Vb and phase currents (Iu, Iv, Iw), as follows: Figure 3 The mapping shown is a three-dimensional mapping, which is pre-stored in the junction temperature estimation calculation unit 32. Additionally, Figure 3 The three-dimensional mapping is a value that was experimentally determined beforehand for the vehicle using electric compressor 1.

[0115] (9-1) Relationship between phase currents (Iu, Iv, Iw) and heat change α

[0116] Next, refer to Figures 4-6 The relationship between phase currents (Iu, Iv, Iw) and thermal variable α is explained. Furthermore, in this case, the effective values ​​of each phase current Iu, Iv, and Iw are used as the phase currents. Also, if phase currents flow through each power semiconductor element 16U to 17W, the wiring pattern 34 also heats up, therefore... Figure 4 As shown, a three-dimensional mapping is constructed so that the larger the phase current, the smaller the thermal variable α. Using... Figure 5, Figure 6 To explain the reasons.

[0117] Figure 5 The heat transfer in the electric compressor 1 for vehicles can be considered in terms of circuitry. In this case, the power source is a semiconductor element 16U-17W, wiring pattern 34, etc. Figure 6 The circuit shown serves as the current source, and the thermal resistance of each component and the housing 2 is represented by resistors R1 to R5. Additionally, the resistance between the junction temperature Tj and the temperature Tth detected by the temperature sensor 22 is the thermal variable α.

[0118] The larger the phase current, the greater the heat generated by the wiring pattern 34, and the temperature Tth detected by the temperature sensor 22 rises with this heat. Therefore, by increasing the phase current, the thermal variable α becomes smaller, thereby allowing the correct junction temperature Tj, which excludes the thermal effects from the wiring pattern 34, to be estimated.

[0119] (9-2) Relationship between battery voltage Vb (power supply voltage) and heat change α

[0120] Next, refer to Figure 7 , Figure 8 The relationship between battery voltage Vb (power supply voltage) and thermal variable α is explained. The higher the battery voltage Vb, the greater the heat generated by each power semiconductor element (16U-17W). Therefore, the thermal influence from other electronic components or wiring pattern 34 is relatively smaller. Figure 7 As shown, a three-dimensional mapping is constructed so that the higher the battery voltage Vb, the greater the thermal variable α. Using... Figure 8 To explain the reasons.

[0121] Furthermore, in the following explanation, it is assumed that the power is generated by a semiconductor element with a heat capacity of 16U to 17W ( Figure 8 90% of the current value of the thermal circuit is drawn away by the refrigerant through the casing 2, and the remaining 10% is transferred to the terminal 37. In addition, if the heat generation of the semiconductor element 16U~17W when the battery voltage Vb is high is set to 50W (consider replacing it with a current of 50A), and when it is low it is 25W (also considered as 25A), and the phase current is the same for both sides at 10Arms, and resistors R1 + R2 are set as resistor group X, and resistors R3 + R4 are set as resistor group Y, then the junction temperature Tj when the battery voltage Vb is high, the temperature Tth detected by the temperature sensor 22, and the thermal variable α are as follows.

[0122] Tj=45X

[0123] Tth=(50×0.1+0.1)Y=5.1Y

[0124] α=(Tj-Tth) / 50=(45X-5.1Y) / 50

[0125] =0.9X-0.102Y (3)

[0126] On the other hand, the junction temperature Tj, the temperature Tth detected by the temperature sensor 22, and the thermal variable α when the battery voltage Vb is low are shown below.

[0127] Tj = 22.5X

[0128] Tth=(25×0.1+0.1)Y=2.6Y

[0129] α=(Tj-Tth) / 25=(22.5X-2.6Y) / 25

[0130] =0.9X-0.104Y (4)

[0131] From equations (3) and (4) above, it can be seen that the thermal variable α increases with the higher the battery voltage Vb. Therefore, in Figure 3 In three-dimensional mapping, such as Figure 7 As shown, increasing the battery voltage Vb increases the thermal variable α, thereby allowing the correct junction temperature Tj to be estimated.

[0132] (10) The junction temperature estimation calculation unit 32 changes the thermal variable α (part 2).

[0133] Next, refer to Figures 9-11 Another control example will be explained whereby the junction temperature estimation calculation unit 32 of the inverter control unit 12 changes the heat variable α in the above equation (2). When the input current Iin flows through the wiring pattern 36, the wiring pattern 36 also heats up. Since this heat is also transmitted to the temperature sensor 22, the temperature Tth detected by the temperature sensor 22 is affected and rises.

[0134] Therefore, the junction temperature estimation calculation unit 32 of this embodiment changes the thermal variable α of the above formula (2) according to the input current Iin (operation state) and corrects the junction temperature Tj in the direction that eliminates the influence of the heating of the wiring pattern 36 on the temperature sensor 22.

[0135] (10-1) Relationship between input current Iin and thermal variable α

[0136] Next, refer to Figure 10 , Figure 11 The relationship between the input voltage Iin and the thermal variable α is explained. Additionally, in each figure, [the following is used]... Figure 5 , Figure 6 The same designation is used to denote parts that perform the same or identical functions. In the case of the embodiment, the relationship between the thermal variable α and the input current Iin is as follows: Figure 9The linear function shown is pre-stored in the junction temperature estimation calculation unit 32. Additionally, Figure 9 The function is a value that was previously obtained through experiments using the electric compressor 1 for the vehicle.

[0137] Alternatively, in this case, replacing heat transfer with a circuit is also considered. That is, the power source for heat is a semiconductor element of 16U-17W or wiring patterns 34, 36, as shown. Figure 11 The circuit is shown as a current source, and the thermal resistance of each component or housing 2 is represented by resistors R1 to R6. Furthermore, let the thermal variable α be the relationship between the junction temperature Tj and the temperature Tth detected by the temperature sensor 22.

[0138] The larger the input current Iin, the greater the heat generated by the wiring pattern 36, and the temperature Tth detected by the temperature sensor 22 rises with this heat. Therefore, by increasing the input current Iin, the thermal variable α becomes smaller, thereby allowing the correct junction temperature Tj to be estimated to eliminate the thermal effects from the wiring pattern 36.

[0139] [Example 2]

[0140] (11) The junction temperature estimation calculation unit 32 changes the heat variable α (part 3).

[0141] Next, refer to Figures 12-14 Another control example will be described, in which the junction temperature estimation calculation unit 32 of the inverter control unit 12 changes the heat variable α in the above formula (2). As described above, each power semiconductor element 16U to 17W is configured to exchange heat with the intake refrigerant via the housing 2. In addition, if the speed NC of the motor 3 increases, the cooling capacity of the intake refrigerant also increases.

[0142] Therefore, the higher the rotational speed NC, the more powerfully each power semiconductor element 16U~17W is cooled, and thus the junction temperature estimation calculation unit 32, as shown in the figure, becomes more efficient. Figure 12 As shown, the higher the rotational speed NC of motor 3, the smaller the thermal variable α becomes, thus correcting for the decrease in junction temperature Tj. Using... Figure 13 , Figure 14 To explain the reasons.

[0143] Additionally, in each figure, the use of... Figure 5 , Figure 6 The same reference numerals are used to indicate parts that perform the same or identical functions. Additionally, in this embodiment, the applicable device is also... Figure 1 The circuit structure of the electric compressor 1 and the inverter device 7 is also the same. Figure 2 Same. However, Figure 2 The operation of the junction temperature estimation calculation unit 32 of the inverter control unit 12 in this embodiment is different from that in the above embodiment.

[0144] In this case, the power is also regarded as a heat source by the semiconductor element 16U~17W. The transfer of this heat (considered as current I) is replaced by the circuit. Then, the current (heat) Ix flowing through the resistor group X composed of resistors R1 and R2 and the current Iy (heat) flowing through the resistor group Y composed of thermal variable α, resistors R3 and R4 can be expressed by the following equations (5) and (6) respectively according to the current division rule.

[0145] Ix={Y / (X+Y)}×I (5)

[0146] Iy={X / (X+Y)}×I (6)

[0147] Here, since resistor group Y includes the thermal resistance of the control substrate 11 made of resin, it becomes a very large value compared to resistor group X. Therefore, even if the resistance values ​​of resistors R2 or R4 change with the rotational speed NC of motor 3, it can be seen from equations (5) and (6) that the current Iy is almost unaffected. That is, the temperature Tth detected by temperature sensor 22 is almost unaffected by the rotational speed NC of motor 3.

[0148] On the other hand, the higher the speed NC of the motor 3, the smaller the resistance values ​​of the variable resistors R2 and R4, and thus the junction temperature Tj decreases. However, as mentioned above, the temperature Tth detected by the temperature sensor 22 does not decrease like the junction temperature Tj, and the difference between the two (Tj and Tth) narrows.

[0149] Therefore, in this embodiment, the junction temperature estimation calculation unit 32 is as follows: Figure 12 As shown, the higher the rotational speed NC of the motor 3, the lower the thermal variable α, and the correction is made in the direction of reducing the junction temperature Tj. Therefore, even in this case, the correct junction temperature Tj can be estimated. Furthermore, even in this case, the temperature protection unit 33 performs the same protection operation as described above based on the estimated junction temperature Tj.

[0150] As described above, in Embodiment 1, when the junction temperature estimation calculation unit 32 estimates the junction temperature Tj, since the correction is performed in the direction that eliminates the influence of the heat generated by other electronic components other than the power semiconductor elements 16U to 17W and the wiring patterns 34 and 36 of the control board 11 on the temperature sensor 22, when the temperature sensor 22 is arranged on the control board 11 as in the embodiment, the influence of the heat generated by other electronic components other than the power semiconductor elements 16U to 17W or the wiring patterns 34 and 36 on the temperature sensor 22 is eliminated, and the junction temperature Tj of the power semiconductor elements 16U to 17W can be estimated more accurately.

[0151] Therefore, even when performing the protection actions described above, the usable area of ​​the power semiconductor element 16U to 17W can be expanded, thereby reducing the component rating and achieving miniaturization and cost reduction.

[0152] In addition, as shown in the embodiment, the junction temperature estimation calculation unit 32 calculates the temperature rise value ΔT by multiplying the loss P of the power semiconductor element 16U to 17W by the thermal variable α, and changes the thermal variable α according to the operating state. Therefore, it is possible to successfully eliminate the influence of the heat generated by other electronic components and the wiring patterns 34 and 36 of the control board 11 on the temperature sensor 22.

[0153] In this case, in the embodiment, the battery voltage Vb (power supply voltage), phase currents (Iu, Iv, Iw), and input current Iin are used in the operating state. Furthermore, in the above embodiment, the thermal variable α is mapped to a value determined by the battery voltage Vb and the phase current; therefore, the thermal variable α can be accurately set according to the interrelated operating states.

[0154] In this embodiment, since a higher battery voltage Vb results in a larger thermal variable α, a correct estimate of the junction temperature Tj can be made. Similarly, a larger phase currents Iu, Iv, and Iw result in a smaller thermal variable α, thus allowing for a correct estimate of the junction temperature Tj. Furthermore, a larger input current Iin results in a smaller thermal variable α, thus enabling a correct estimate of the junction temperature Tj.

[0155] Furthermore, in the vehicle electric compressor 1 used in high-temperature environments, such as the embodiment, the motor 3 can be operated using the inverter device 1 of the embodiment, which enables extremely effective overheat protection.

[0156] On the other hand, in the invention of Embodiment 2, the higher the rotational speed NC of the motor 3, the lower the junction temperature Tj is corrected, thus enabling accurate estimation of the junction temperature Tj. In this embodiment, the junction temperature estimation calculation unit 32 calculates the temperature rise ΔT by multiplying the power semiconductor element 16U-17W loss P by the heat variable α, and modifies the heat variable α so that the higher the rotational speed NC of the motor, the smaller the heat variable α becomes, thus enabling accurate estimation of the junction temperature Tj.

[0157] Therefore, even when performing the protection actions described above, the usable area of ​​the power semiconductor element 16U to 17W can still be expanded, thereby reducing the component rating and achieving miniaturization and cost reduction.

[0158] [Example 3]

[0159] (12) Control of gate resistance variation

[0160] Next, refer to Figures 17-19 This describes the control of changing the gate resistance of each semiconductor switching element 18 by the inverter control unit 12. In this embodiment, the inverter control unit 12 changes the gate resistance of the semiconductor switching elements 18 that constitute each power semiconductor element 16U to 17W based on the junction temperature Tj estimated by the junction temperature estimation calculation unit 32 as described above.

[0161] As described above, when driving the gate of the semiconductor switching element 18 (IGBT), a surge voltage ΔV (=L) is generated through the inductance L of the wiring busbar when the switch changes from on to off (cutoff). di / dt)( Figure 15 (Left side). On the other hand, the breakdown voltage of the semiconductor switching element 18 (IGBT) decreases as the junction temperature Tj decreases ( Figure 15 (Right side). Furthermore, when the surge voltage ΔV exceeds the withstand voltage (element withstand voltage) of the semiconductor switching element 18, there is a risk of damage to the element.

[0162] Therefore, a connection is made on the gate of the semiconductor switching element 18. Figure 2 The gate resistor 39 shown in the figure is required to passivate the falling edge of the signal voltage supplied to the gate by the gate resistor 39. However, if the resistance value of the gate resistor 39 is increased, the current cut-off speed when the semiconductor switching element 18 is turned off will be slower, resulting in increased losses. Figure 16 On the other hand, when the semiconductor switching element 18 operates, it generates heat due to losses, so the junction temperature Tj gradually increases, and the withstand voltage (element withstand voltage) also increases accordingly.

[0163] Therefore, in this embodiment, the inverter control unit 12 changes the resistance value of the gate resistor of the semiconductor switching element 18 constituting each power semiconductor element 16U to 17W based on the junction temperature Tj estimated by the junction temperature estimation calculation unit 32 as described above. Hereinafter, the control of the gate resistor change by the inverter control unit 12 will be specifically described.

[0164] In this embodiment, the inverter control unit 12 has a gate resistance changing unit 41. Figure 17 This is a circuit diagram illustrating an example of the structure of the gate resistance changing unit 41 of the inverter control unit 12 in this embodiment. Additionally, in Figures 17-19 In the middle, used with Figures 1 to 14 Circuits represented by the same symbol perform the same or identical functions, and basic circuits are also similar. Figure 2 Same. However, in this embodiment, the gate resistor 39 is replaced with... Figure 17 The variable resistor device 42 shown.

[0165] Here, although in Figure 17The semiconductor switching element 18 of the power semiconductor element 17U is shown as an example, but for all the power semiconductor elements 16U to 17W, the same variable resistor device 42 is also connected to the gate and controlled by the inverter control unit 12.

[0166] Furthermore, the variable resistor device 42, the gate driver 29, and the PWM control unit 27 constitute the gate resistance changing unit 41 in this embodiment. Additionally, regarding the internal structure and control program of the gate driver 29 and the PWM control unit 27, additional structures and control programs required to implement the above embodiments are added, or modifications are made to the above embodiments.

[0167] In this embodiment, the gate resistance changing unit 41 changes the resistance value of the gate resistor of the semiconductor switching element 18 (which is a power semiconductor element 16U to 17W) based on the junction temperature Tj estimated by the junction temperature estimation calculation unit 32. In this case, the gate resistance changing unit 41 operates in a direction where a lower junction temperature Tj results in a higher resistance value for the variable resistor 42, and a higher junction temperature Tj results in a lower resistance value for the variable resistor 42.

[0168] Figure 18 This section illustrates an example of the specific circuitry surrounding the gate resistance changing section 41, which includes the aforementioned variable resistor device 42. The gate resistance changing section 41 in this example comprises: a turn-on signal generating switch S0, which is a MOSFET with its source connected to the gate voltage power supply Vcc of the semiconductor element 18; a turn-off signal generating switch S1, whose source is grounded and whose drain is connected to the drain of the turn-on signal generating switch S0, and which is also a MOSFET; a resistor R10 connected between the connection point of the drains of the turn-on signal generating switches S0 and S1 and the gate of the semiconductor switching element 18; and another resistor R2, one end of which is connected between the resistor R10 and the gate of the semiconductor switching element 18, and the other end of which is connected to the drain of another turn-off signal generating switch S2, which is also a MOSFET.

[0169] The source of the aforementioned disconnect signal generating switch S2 is grounded, and the emitter of the semiconductor switching element 18 of the power semiconductor element 17U is also connected to and grounded to the sources of the disconnect signal generating switches S1 and S2. Thus, the on signal generating switch S0 and the off signal generating switch S1 are connected to the gate of the semiconductor switching element 18 via resistor R10, and the off signal generating switch S2 is connected to the gate of the semiconductor switching element 18 via resistor R20. Furthermore, the above structure is the same for the power semiconductor elements 17V and 17W semiconductor switching elements 18. The same applies to the power semiconductor elements 16U to 16W semiconductor switching elements 18, but it is assumed that the emitter is not grounded.

[0170] In this configuration, the on-signal generation switch S0 and the off-signal generation switches S1 and S2 are included in the gate driver 29. Additionally, the resistors R10 and R20 constitute the variable resistor device 42 of this embodiment, and these resistors R10 and R20 are disposed near the gate of the semiconductor switching element 18. Furthermore, the resistance values ​​of resistors R10 and R20 are different, with the resistance value of R10 being greater than that of R20.

[0171] Furthermore, the PWM control unit 27 inputs a signal to the gate of the turn-on signal generation switch S0 to turn on the semiconductor switching element 18 (IGBT), and inputs a signal to the turn-off signal generation switches S1 and S2 to turn off the semiconductor switching element 18 (IGBT). In this case, the PWM control unit 27 switches the signal that turns off the semiconductor switching element 18 to each of the turn-off signal generation switches S1 and S2 based on the junction temperature Tj estimated by the junction temperature estimation calculation unit 32, and outputs it. Thus, when switching the turn-off signal generation switches S1 and S2 to turn on and off the semiconductor switching element 18, the resistance value of the gate resistor of the semiconductor switching element 18 is changed.

[0172] Next, refer to Figure 19 illustrate Figure 18 The operation of the gate resistance changing section 41. Figure 19 The bottom layer represents the collector-emitter voltage of the semiconductor switching element 18, the top layer represents the on / off state of the switch S0 for generating the on signal, and the second and third layers from the top represent the on / off states of the switches S1 and S2 for generating the off signal.

[0173] When the semiconductor switching element 18 of the power semiconductor elements 16U to 17W is turned on (closed), the gate driver 29 receives the rising edge of the drive signal output from the PWM control unit 27, outputs the signal that turns on the semiconductor switching element 18 to the turn-on signal generation switch S0, and turns on the turn-on signal generation switch S0. On the other hand, no signal that turns off the semiconductor switching element 18 is output, thereby turning off the turn-off signal generation switches S1 and S2. Figure 19 During the period when the switch S0 for generating the turn-on signal is turned on, the switches S1 and S2 for generating the turn-off signal are turned off. As a result, current flows through the gate of the semiconductor switching element 18 in the path of the gate voltage power supply Vcc, the switch S0 for generating the turn-on signal, the resistor R10, the gate of the semiconductor switching element 18, the emitter, and ground, and the semiconductor switching element 18 is turned on (connected).

[0174] Next, when the semiconductor switching element 18 is turned off, the gate driver 29 (which constitutes the gate resistance changing unit 41 as described above) receives the falling edge of the drive signal output from the PWM control unit 27 and outputs a signal to turn off the semiconductor switching element 18 to the off signal generating switch S1 (or S2), thus turning on the off signal generating switch S1 (or S2). On the other hand, no signal is output to turn on the semiconductor switching element 18, thereby turning off the on signal generating switch S0. Figure 19 During the period when S1 (or S2) is turned on, the switch S0 for generating the turn-on signal is turned off. The gate driver 29 (gate resistance changing unit 41) switches the output target based on the junction temperature Tj estimated by the junction temperature estimation calculation unit 32 for the signal that turns off the semiconductor switching element 18.

[0175] In this embodiment, when the junction temperature Tj is low (at a low temperature) and below a predetermined value T1, the gate driver 29 receives the falling edge of the drive signal output from the PWM control unit 27 and outputs a signal to the disconnect signal generation switch S1 to disconnect the semiconductor switching element 18, thus turning on the disconnect signal generation switch S1 and turning off the disconnect signal generation switch S2. As a result, the charge stored in the gate of the semiconductor switching element 18 is released through the path of the resistor element R10, the disconnect signal generation switch S1, and ground, thus disconnecting the semiconductor switching element 18. Therefore, at this low temperature, the resistance value of the gate resistor of the semiconductor switching element 18 becomes the resistance value of the resistor element R10, which has a larger resistance value, thereby suppressing surge voltage.

[0176] On the other hand, when the junction temperature Tj rises and becomes a predetermined value T2 or higher than the aforementioned predetermined value T1, when the semiconductor switching element 18 is turned off, the gate driver 29 receives the falling edge of the drive signal output from the PWM control unit 27 and outputs a signal to the turn-off signal generation switch S2 to turn off the semiconductor switching element 18, thus turning on the turn-off signal generation switch S2 and turning off the turn-off signal generation switch S1. As a result, the charge stored in the gate of the semiconductor switching element 18 is released through the path of the resistor element R20, the turn-off signal generation switch S2, and ground. Therefore, when the semiconductor switching element 18 is turned off, the resistance value of the gate resistor of the semiconductor switching element 18 at high temperature becomes the resistance value of the resistor element R20, which has a smaller resistance value. Therefore, although the surge voltage increases, the withstand voltage of the semiconductor switching element 18 also increases at this high temperature, thus preventing element damage. Furthermore, losses can be suppressed.

[0177] Furthermore, when the junction temperature Tj drops and becomes below a predetermined value T1, when the semiconductor switching element 18 is turned off, the gate driver 29 receives the falling edge of the drive signal output from the PWM control unit 27, outputs a signal to the turn-off signal generation switch S1 to turn off the semiconductor switching element 18, switches to turn on the turn-off signal generation switch S1, and turns off the turn-off signal generation switch S2.

[0178] As in the embodiments described above, the junction temperature Tj of the semiconductor switching element 18 of the power semiconductor element 16U to 17W can be accurately estimated, and the withstand voltage variation of the semiconductor switching element 18 of the power semiconductor element 16U to 17W can be accurately controlled.

[0179] Furthermore, in this embodiment, as described above, a gate resistance changing unit 41 is provided on the inverter control unit 12. This gate resistance changing unit 41 changes the resistance value of the gate resistance of the semiconductor switching element 18, which is a power semiconductor element 16U to 17W. Based on the junction temperature Tj estimated by the junction temperature estimation calculation unit 32, the gate resistance changing unit 41 changes the resistance value of the gate resistance of the semiconductor switching element 18, thereby achieving optimal operation that takes into account the withstand voltage of the semiconductor switching element 18.

[0180] Furthermore, in the embodiment, the lower the junction temperature Tj of the semiconductor switching element 18 estimated by the junction temperature estimation calculation unit 32, the larger the resistance value of the gate resistor of the semiconductor switching element 18; the higher the junction temperature Tj, the smaller the resistance value of the gate resistor of the semiconductor switching element 18. Therefore, when the junction temperature Tj is low and the withstand voltage of the semiconductor switching element 18 is reduced, the resistance value of the gate resistor can be increased and the surge voltage can be reduced. When the junction temperature Tj is high and the withstand voltage of the semiconductor switching element 18 is increased, the resistance value of the gate resistor can be reduced and the generated losses can be reduced.

[0181] Therefore, it is possible to avoid damage to power semiconductor components of 16U to 17W caused by surge voltage while suppressing losses and achieving efficient operation.

[0182] In this case, in the embodiment, a variable resistor device 42 connected to the gate of the semiconductor switching element 18 is provided in the gate resistance changing section 41. The resistance value of the variable resistor device 42 is changed according to the junction temperature Tj estimated by the junction temperature estimation calculation section 32. At the same time, the lower the junction temperature Tj, the larger the resistance value of the variable resistor device 42, and the higher the junction temperature Tj, the smaller the resistance value of the variable resistor device 42. Therefore, it is possible to prevent damage to the power semiconductor element 16U to 17W caused by surge voltage and to suppress the generation loss of the power semiconductor element 16U to 17W.

[0183] Specifically, in this embodiment, a switch S0 for generating a conduction signal is provided on the variable resistor device 42. The switch S0 is connected to the gate of the semiconductor switching element 18 and is used to input a conduction signal to the gate. Two switches S1 and S2 for generating a disconnection signal are respectively connected to the gate and are used to input a disconnection signal to the gate. Two resistors, R10 and R20, are connected to switches S1 and S2, respectively, for generating disconnection signals, and have different resistance values. When the semiconductor switching element 18 is disconnected, the gate resistance changing unit 41 switches and turns on each of the disconnection signal generating switches S1 and S2 according to the junction temperature Tj, thereby changing the resistance value of the gate resistance of the semiconductor switching element 18. When the junction temperature Tj is below a predetermined value T1, the disconnection signal generating switch S1, which is connected to the resistor R10 with a larger resistance value, is turned on. When the junction temperature Tj is above a predetermined value T2, which is higher than the predetermined value T1, the disconnection signal generating switch S2, which is connected to the resistor R20 with a smaller resistance value, is turned on. Therefore, it is possible to prevent damage to the power semiconductor elements 16U to 17W caused by the surge voltage when the semiconductor switching element 18 is disconnected, and to suppress the generation loss of the power semiconductor elements 16U to 17W.

[0184] In addition, in the above embodiments, the three-dimensional mapping of thermal variable α is constructed using battery voltage Vb (power supply voltage) and phase current, but it is not limited to this. For example, the three-dimensional mapping can also be constructed using battery voltage Vb and input current Iin.

[0185] Furthermore, in the embodiments, a power semiconductor element 16U to 17W composed of a composite of semiconductor switching element 18 (IGBT, MOSFET) and return diode 19 is used as an example for description, but it is not limited thereto. The present invention is also effective for inverter circuits that only do not have semiconductor switching elements (IGBT, MOSFET).

[0186] Furthermore, the present invention is illustrated in the embodiments using an inverter device that drives an electric motor of an electric compressor mounted on a vehicle, but the invention of aspects 1 to 9 is not limited thereto, and the present invention is effective in all inverter devices using inverter circuits with power semiconductor switching elements.

[0187] Furthermore, the circuit of the gate resistance changing unit 41 shown in the above embodiment is not limited to the structure of the embodiment, and can be modified as long as it does not depart from the spirit of the present invention. In particular, in the embodiment, the variable resistance device 42 is composed of two switches for generating disconnect signals and two resistive elements. However, by using more switches and resistive elements, and switching the switches according to the junction temperature Tj, the gate resistance of the semiconductor switching element 18 of the power semiconductor element 16U to 17W can be changed more precisely.

[0188] Label Explanation

[0189] 1 Electric compressor

[0190] 2. Shell

[0191] 3. Electric motor

[0192] 4 suction port

[0193] 6. Compression Elements

[0194] 7. Inverter Unit

[0195] 8 Inverter Circuit

[0196] 11 Control board

[0197] 12 Inverter Control Unit

[0198] 16U~17W power semiconductor devices

[0199] 18 Semiconductor switching elements

[0200] 22 Temperature sensor (temperature detector)

[0201] 23 Shunt resistor (phase current detector)

[0202] 26. Electric Motor Control Unit

[0203] 27 PWM Control Unit

[0204] 28 Current Detection Section

[0205] 29 Gate Driver

[0206] 31 Loss Calculation Department

[0207] 32 Junction Temperature Estimation Calculation Section

[0208] 33 Temperature Protection Section

[0209] 41 Gate Resistance Variation Section

[0210] 42 Variable Resistor Device

[0211] B High-voltage battery

[0212] R10 and R20 resistors

[0213] Switch for generating S0 conduction signal

[0214] S1 and S2 are switches used to disconnect signal generation.

Claims

1. An inverter device comprising an inverter circuit having power semiconductor elements and an inverter control unit for driving the power semiconductor elements, characterized in that, It is equipped with a temperature detector for detecting the temperature near the power semiconductor element. The inverter control unit has: A loss calculation unit calculates the loss P of the power semiconductor element; and The junction temperature estimation calculation unit adds the temperature rise value ΔT obtained by the loss P of the power semiconductor element calculated by the loss calculation unit to the temperature Tth detected by the temperature detector, thereby estimating the junction temperature Tj of the power semiconductor element. When estimating the junction temperature Tj, the junction temperature estimation calculation unit calculates the temperature rise ΔT by multiplying the power semiconductor element loss P by a predetermined thermal variable α, and... Based on the operating state, the thermal variable α is changed to correct the direction in which the heating effect of the wiring pattern of electronic components other than the power semiconductor element and / or the control substrate is excluded from the effect on the temperature detector.

2. The inverter device as described in claim 1, characterized in that, The temperature detector is mounted on the control board on which the other electronic components are installed.

3. The inverter device as described in claim 1, characterized in that, The operating state includes any one of the power supply voltage, phase current, and input current, or a combination thereof, or all of them.

4. The inverter device as described in claim 3, characterized in that, The thermal variable α is mapped to a value determined by at least two of the power supply voltage, the phase current, and the input current.

5. The inverter device as described in claim 3 or 4, characterized in that, The higher the power supply voltage, the greater the thermal variable α.

6. The inverter device as described in claim 3 or 4, characterized in that, The larger the phase current, the smaller the thermal variable α.

7. The inverter device as described in claim 3 or 4, characterized in that, The larger the input current, the smaller the thermal variable α.

8. The inverter device according to any one of claims 1 to 4, characterized in that, When the junction temperature Tj of the power semiconductor element, as estimated by the junction temperature estimation calculation unit, exceeds a predetermined value, the inverter control unit performs a predetermined protection action.

9. An electric compressor for vehicles, characterized in that, It includes an electric motor operated by an inverter device according to any one of claims 1 to 4 and a housing housing the electric motor, wherein the power semiconductor element and the low-temperature portion of the housing are configured to exchange heat.

10. An electric compressor for a vehicle, comprising: An inverter device, comprising an inverter circuit having power semiconductor elements and an inverter control unit for driving the power semiconductor elements; an electric motor operated by the inverter device; and a housing housing the electric motor, wherein the power semiconductor elements are configured to exchange heat with the intake refrigerant via the housing. The electric compressor for vehicles is characterized in that... It is equipped with a temperature detector for detecting the temperature near the power semiconductor element. The inverter control unit has: A loss calculation unit calculates the loss P of the power semiconductor element; as well as The junction temperature estimation calculation unit adds the temperature rise value ΔT obtained by the loss P of the power semiconductor element calculated by the loss calculation unit to the temperature Tth detected by the temperature detector, thereby estimating the junction temperature Tj of the power semiconductor element. When estimating the junction temperature Tj, the junction temperature estimation calculation unit multiplies the power semiconductor element loss P by a predetermined thermal variable α to calculate the temperature rise value ΔT, and modifies the thermal variable α to correct the junction temperature Tj in a direction that decreases as the motor speed increases.

11. The electric compressor for vehicles as claimed in claim 10, characterized in that, When the junction temperature Tj of the power semiconductor element, as estimated by the junction temperature estimation calculation unit, exceeds a predetermined value, the inverter control unit performs a predetermined protection action.

12. An inverter device comprising an inverter circuit having power semiconductor elements and an inverter control unit for driving the power semiconductor elements, characterized in that, It is equipped with a temperature detector for detecting the temperature near the power semiconductor element. The inverter control unit has: A loss calculation unit calculates the loss P of the power semiconductor element; The junction temperature estimation calculation unit adds the temperature rise value ΔT obtained by adding the temperature Tth detected by the temperature detector to the temperature rise value ΔT obtained by the loss P of the power semiconductor element calculated by the loss calculation unit, thereby estimating the junction temperature Tj of the power semiconductor element. as well as A gate resistance changing unit that changes the resistance value of the gate resistor of the power semiconductor element. When estimating the junction temperature Tj, the junction temperature estimation calculation unit corrects for the influence of heat generation from electronic components other than the power semiconductor element and / or the wiring pattern of the control substrate on the temperature detector. The gate resistance changing unit changes the resistance value of the gate resistance of the power semiconductor element based on the junction temperature Tj estimated by the junction temperature estimation calculation unit.

13. The inverter device or electric compressor for vehicles as described in claim 12, characterized in that, The lower the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit, the larger the resistance value of the gate resistor of the power semiconductor element becomes by the gate resistor changing unit; the higher the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit, the smaller the resistance value of the gate resistor of the power semiconductor element becomes by the gate resistor changing unit.

14. The inverter device or electric compressor for vehicles as described in claim 12 or 13, characterized in that, The gate resistance changing unit has: A variable resistor device connected to the gate of the power semiconductor element. The resistance value of the variable resistor is changed based on the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit.

15. The inverter device or electric compressor for vehicles as described in claim 14, characterized in that, The lower the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit, the greater the resistance value of the variable resistor device becomes; conversely, the higher the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit, the smaller the resistance value of the variable resistor device becomes.

16. The inverter device or electric compressor for vehicles as described in claim 14, characterized in that, The variable resistor device has: A switch for generating a conduction signal is connected to the gate of the power semiconductor element and is used to input a conduction signal to the gate. A disconnect signal generating switch is connected to the gate of the power semiconductor element and is used to input a disconnect signal to the gate; as well as Multiple resistive elements, each with a different resistance value, are connected to multiple switches used to generate disconnect signals. When the power semiconductor element is disconnected, the gate resistance changing unit switches and turns on each disconnection signal generating switch according to the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit, thereby changing the resistance value of the gate resistance of the power semiconductor element.

17. The inverter device or electric compressor for vehicles as described in claim 16, characterized in that, When the junction temperature Tj of the power semiconductor element, as estimated by the junction temperature estimation calculation unit, is below a predetermined value T1, the gate resistance changing unit turns on the switch for generating the disconnect signal, which is connected to the resistor element with a large resistance value. When the junction temperature Tj of the power semiconductor element estimated by the junction temperature estimation calculation unit is a predetermined value T2 or higher than the predetermined value T1, the gate resistance changing unit turns on the switch for generating the disconnect signal connected to the resistor element with a small resistance value.

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