Power conversion device and motor module

Abstract

The present invention comprises: a power converter in which each of three phases has an upper arm and a lower arm; and a signal generator which generates signals for driving the respective upper and lower arms of the three phases in the power converter by an energization method that has an energization period of 120-180° and in which PWM control is performed on one of the upper arms and the lower arms. The signal generator comprises a switching unit that, under predetermined conditions, switches the drive mode of the power converter between a first mode in which the upper arms are controlled by the PWM control and a second mode in which the lower arms are controlled by the PWM control.

Description

Power conversion device and motor module

[0001] The present disclosure relates to a power conversion device and a motor module.

[0002] A power conversion device is known that includes a power converter having an upper arm and a lower arm for each of three phases. For example, Patent Document 1 discloses a technology for driving a power converter that supplies power to a motor using a 120-degree conduction method.

[0003] Japanese Patent Application Laid-Open No. 2004-201453

[0004] In the technology described in Patent Document 1, the phases corresponding to the electrical angles are controlled by PWM (Pulse Width Modulation), which may cause overheating of the elements constituting the power converter due to switching loss. This is not limited to the 120-degree conduction method, but is also true for the 150-degree conduction method and the 180-degree conduction method.

[0005] The present disclosure provides a technique that can prevent overheating of elements that make up a power converter.

[0006] A power conversion device according to one aspect of the present disclosure includes a power converter having an upper arm and a lower arm for each of three phases, and a signal generator that generates signals to drive the upper and lower arms of the three phases of the power converter using a current conduction method having a current conduction period of 120 degrees or more and 180 degrees or less, in which one of the upper and lower arms is PWM-controlled. The signal generator includes a switching unit that switches, under predetermined conditions, between a first mode in which the upper arm is PWM-controlled and a second mode in which the lower arm is PWM-controlled, as drive modes of the power converter.

[0007] According to the present disclosure, it is possible to prevent overheating of elements that constitute a power converter.

[0008] FIG. 1 is a diagram illustrating an example of the configuration of a motor module according to an embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a power converter in a power conversion device according to an embodiment. FIG. 3 is a diagram illustrating an example of a gate signal output in a first mode by a signal generator in the power conversion device according to an embodiment. FIG. 4 is a diagram illustrating an example of a gate signal output in a second mode by the signal generator in the power conversion device according to an embodiment. FIG. 5 is a diagram illustrating switching of a drive mode based on a predetermined time condition by a switching unit in the signal generator of the power conversion device according to an embodiment. FIG. 6 is a diagram illustrating timing of switching of a drive mode by a switching unit in the signal generator of the power conversion device according to an embodiment. FIG. 7 is a flowchart illustrating an example of a process of switching a drive mode based on a predetermined time condition by a switching unit in the signal generator of the power conversion device according to an embodiment. FIG. 8 is a diagram illustrating switching of a drive mode based on a predetermined first temperature condition by a switching unit in the signal generator of the power conversion device according to an embodiment. FIG. 9 is a flowchart illustrating an example of a process of switching a drive mode based on a predetermined first temperature condition by a switching unit in the signal generator of the power conversion device according to an embodiment. FIG. 10 is a diagram illustrating switching of a drive mode in a U-phase protection mode by a switching unit in the signal generator of the power conversion device according to an embodiment. FIG. 11 is a diagram showing a U-phase switching circuit by a switching unit in a signal generator of a power conversion device according to an embodiment. Ｈ V Ｌ FIG. 12 is a diagram for explaining switching of drive modes in a protection mode. FIG. 12 is a flowchart showing an example of a process for switching drive modes based on a predetermined second temperature condition by a switching unit in a signal generator of a power conversion device according to an embodiment. FIG. 13 is a diagram for explaining switching of drive modes based on a predetermined time condition by a switching unit in a power conversion device according to an embodiment when a current conduction period is 150 degrees. FIG. 14 is a diagram for explaining switching of drive modes based on a predetermined time condition by a switching unit in a power conversion device according to an embodiment when a current conduction period is 180 degrees. FIG. 15 is a diagram showing an example of the hardware configuration of a signal generator of a power conversion device according to an embodiment.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a power conversion device and a motor module disclosed in the present application will be described in detail with reference to the accompanying drawings. However, the disclosed technology is not limited to these embodiments.

[0010] 1. Motor Module> Fig. 1 is a diagram showing an example of the configuration of a motor module according to an embodiment. As shown in Fig. 1, a motor module 100 according to an embodiment includes a motor 2, a position detector 3, and a power conversion device 5. The motor 2 is a three-phase motor.

[0011] The position detector 3 detects the rotor position θ of the motor 2. ｅ and outputs the detected position θe to the power conversion device 5. ｅ is the electrical angle of the rotor of the motor 2. The position detector 3 is, for example, a magnetic sensor using a Hall element or a resolver.

[0012] The position detector 3 detects the rotor position θ of the motor 2. ｍ The position θ of the rotor of the motor 2 may be detected by an optical encoder. ｍ is the mechanical angle of the rotor of the motor 2. The power conversion device 5 may also have a function of performing position sensorless control, in which case the motor module 100 does not need to be provided with a position detector 3.

[0013] The power conversion device 5 supplies power to the motor 2 to drive the motor 2. The power conversion device 5 drives the motor 2 using a current supply method having a current supply period of 120 degrees or more and 180 degrees or less. For example, the power conversion device 5 drives the motor 2 using a current supply method having a predetermined current supply period within the current supply period of 120 degrees or more and 180 degrees or less.

[0014] The power conversion device 5 may be configured to drive the motor 2 using a current conduction method having a current conduction period according to set parameters from among a current conduction period of 120 degrees or more and 180 degrees or less. For example, the power conversion device 5 may be configured to drive the motor 2 by selectively using the 120-degree conduction method, the 150-degree conduction method, and the 180-degree conduction method according to parameters.

[0015] The energization method used by the power conversion device 5 is a method of PWM controlling one of an upper arm and a lower arm, which will be described later, and will be described in detail below.

[0016] 1, the power conversion device 5 includes a power converter 10, a current detector 20, and a signal generator 50. The power converter 10, the current detector 20, and the signal generator 50 will be described below in that order.

[0017] <2.1. Power Converter 10> The power converter 10 receives a gate signal S output from a signal generator 50. ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ The motor 2 is supplied with electric power according to the above.

[0018] 2 is a diagram showing an example of the configuration of the power converter 10 in the power conversion device 5 according to the embodiment. As shown in FIG. 2, the power converter 10 includes an upper arm 11 １ , 11 ２ , 11 ３ and the lower arm 12 １ , 12 ２ , 12 ３ and temperature sensor 15 １ , 15 ２ , 15 ３ , 15 ４ , 15 ５ , 15 ６ and a gate driver 16.

[0019] In the power converter 10, filters (not shown) made up of coils and capacitors are provided for the U-phase, V-phase, and W-phase, but the power converter 10 may be configured without filters.

[0020] Upper arm 11 １ and lower arm 12 １ The upper arm 11 constitutes a half-bridge circuit of the U phase. ２ and lower arm 12 ２ constitutes a V-phase half-bridge circuit, and the upper arm 11 ３ and the W-phase lower arm 12 ３and form a W-phase half-bridge circuit.

[0021] Upper arm 11 １ is the switching element 13 １ and the switching element 13 １ Diode 14 connected in antiparallel to １ The lower arm 12 １ is the switching element 13 ２ and the switching element 13 ２ Diode 14 connected in antiparallel to ２ It is equipped with:

[0022] Upper arm 11 ２ is the switching element 13 ３ and the switching element 13 ３ Diode 14 connected in antiparallel to ３ The lower arm 12 ２ is the switching element 13 ４ and the switching element 13 ４ Diode 14 connected in antiparallel to ４ It is equipped with:

[0023] Upper arm 11 ３ is the switching element 13 ５ and the switching element 13 ５ Diode 14 connected in antiparallel to ５ The lower arm 12 ３ is the switching element 13 ６ and the switching element 13 ６ Diode 14 connected in antiparallel to ６ It is equipped with:

[0024] Each switching element 13 １ , 13 ２ , 13 ３ , 13 ４ , 13 ５ , 13 ６ are switching elements such as an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor (MOSFET).

[0025] In addition, each switching element 13 １ , 13 ２ , 13 ３ , 13 ４ , 13 ５ , 13 ６ The switching element may be, for example, a switching element formed of a silicon-based material or a switching element formed of a wide bandgap semiconductor. The wide bandgap semiconductor may be, for example, silicon carbide (SiC), gallium nitride (GaN), gallium oxide (GaO), or the like. ２ O ３ ), or diamonds.

[0026] In the following, the upper arm 11 １ , 11 ２ , 11 ３ When each of these is shown without being individually distinguished, it will be referred to as the upper arm 11 and the lower arm 12. １ , 12 ２ , 12 ３ When each of the switching elements 13 is not individually indicated, they may be referred to as the lower arm 12. １ , 13 ２ , 13 ３ , 13 ４ , 13 ５ , 13 ６ When each of these elements is not individually indicated, they may be referred to as a switching element 13. １ , 14 ２ , 14 ３ , 14 ４ , 14 ５ , 14 ６ When each of these is referred to without being individually distinguished, they may be referred to as diodes 14.

[0027] temperature sensor 15 １ upper arm 11 １ Temperature Td １ and the upper arm 11 １ Temperature Td １ The temperature sensor 15 outputs information indicating the temperature. ２ is the lower arm 12 １ Temperature Td ２and the lower arm 12 １ Temperature Td ２ The temperature sensor 15 outputs information indicating the temperature. ３ upper arm 11 ２ The ambient temperature Td ３ and the upper arm 11 ２ Temperature Td ３ The temperature sensor 15 outputs information indicating the temperature. ４ is the lower arm 12 ２ Temperature Td ４ and the lower arm 12 ２ Temperature Td ４ Outputs information indicating the above.

[0028] temperature sensor 15 ５ upper arm 11 ３ Temperature Td ５ and the upper arm 11 ３ Temperature Td ５ The temperature sensor 15 outputs information indicating the temperature. ６ is the lower arm 12 ３ Temperature Td ６ and the lower arm 12 ３ Temperature Td ６ In the following, the temperature sensor 15 １ , 15 ２ , 15 ３ , 15 ４ , 15 ５ , 15 ６ When each of these is not individually indicated, they may be referred to as the temperature sensor 15. １ , Td ２ , Td ３ , Td ４ , Td ５ , Td ６ When each of these is referred to without being individually distinguished, they may be referred to as temperature Td.

[0029] When the upper arm 11 and the lower arm 12 are each molded, the temperature sensor 15 may be molded integrally with the upper arm 11 and the lower arm 12. The temperature sensor 15 detects the temperature of the switching element 13 as the temperature Td of the upper arm 11 and the lower arm 12, but the temperature sensor 15 may also detect the temperature of either the switching element 13 or the diode 14, whichever has a higher temperature, as the temperature Td of the upper arm 11 and the lower arm 12.

[0030] The gate driver 16 receives the gate signal S ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ is amplified and the amplified gate signal S ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ Upper arm 11 １ , 11 ２ , 11 ３ and the lower arm 12 １ , 12 ２ , 12 ３ Output to the gate.

[0031] The gate driver 16 outputs the amplified gate signal S ＵＨ The upper arm 11 of the U phase １ By outputting to the switching element 13 １ is driven, and the amplified gate signal S ＵＬ The lower arm 12 of the U phase １ By outputting to the switching element 13 ２ The gate driver 16 drives the amplified gate signal S ＶＨ V-phase upper arm 11 ２ By outputting to the switching element 13 ３ is driven, and the amplified gate signal S ＶＬ V-phase lower arm 12 ２ By outputting to the switching element 13 ４ Drives.

[0032] The gate driver 16 outputs the amplified gate signal SＷＨ W-phase upper arm 11 ３ By outputting to the switching element 13 ５ is driven, and the amplified gate signal S ＷＬ W-phase lower arm 12 ３ By outputting to the switching element 13 ６ Drives.

[0033] <2.2. Current detector 20> The current detector 20 detects a three-phase current value I ＵＶＷ and the detected three-phase current value I ＵＶＷ to the signal generator 50. The three-phase current values ​​I ＵＶＷ is the instantaneous value of the U-phase current I Ｕ and the instantaneous value I of the V-phase current Ｖ and the instantaneous value I of the W-phase current Ｗ Includes:

[0034] In the example shown in FIG. 1, the current detector 20 is, for example, a current sensor using a Hall element or a current sensor using a current transformer called a CT (Current Transformer), but may also be a current sensor using a shunt resistor.

[0035] <2.3. Signal Generator 50> The signal generator 50 generates gate signals S that control the upper arm 11 and the lower arm 12 of the three phases of the power converter 10 in a specific energization method. ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ The signal generator 50 generates the generated gate signal S ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ to the power converter 10. As a result, power is supplied from the power converter 10 to the motor 2.

[0036] The specific energization method is a method having an energization period of 120 degrees or more and 180 degrees or less, and is a method of PWM controlling one of the upper arm 11 and the lower arm 12. In the following, a 120-degree energization method in which the energization period is 120 degrees will be described as an example, but similar control can be performed even when the energization period is other than 120 degrees.

[0037] The signal generator 50 includes a switching element control unit 51 and a switching unit 52. The switching element control unit 51 generates a gate signal S ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ Generate.

[0038] The switching element control unit 51 detects, for example, the position θ ｅ and the three-phase current value I detected by the current detector 20. ＵＶＷ Based on this, the gate signal S ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ Generate.

[0039] The switching element control unit 51 detects, for example, the position θ ｅ and the three-phase current value I detected by the current detector 20. ＵＶＷ Position θ ｅ The switching element control unit 51 generates a current command based on the difference between the electrical angular velocity and the speed command, and converts the generated current command into a value in a rotating coordinate system (for example, a dq coordinate system) based on the three-phase current value I ＵＶＷ The switching element control unit 51 generates a voltage command based on the difference between the position θ detected by the position detector 3 and the ｅ During the conduction period of each phase according to ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , SＷＬ Generate.

[0040] The switching element control unit 51 can switch between a first mode in which the upper arm 11 is PWM-controlled and a second mode in which the lower arm 12 is PWM-controlled as the drive mode of the power converter 10. FIG. 3 shows the gate signal S output by the signal generator 50 of the power conversion device 5 according to the embodiment in the first mode. ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ FIG.

[0041] As shown in FIG. 3, the gate signal S output in the first mode ＵＨ , S ＶＨ , S ＷＨ are output from the signal generator 50 as PWM signals in mutually different 120-degree conduction sections. Also, the gate signal S output in the first mode ＵＬ , S ＶＬ , S ＷＬ is output from the signal generator 50 as a signal that is always at a high level in the mutually different 120-degree energization sections.

[0042] FIG. 4 shows the gate signal S output by the signal generator 50 of the power conversion device 5 according to the embodiment in the second mode. ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ FIG.

[0043] As shown in FIG. 4, the gate signal S output in the second mode ＵＨ , S ＶＨ , S ＷＨ is output from the signal generator 50 as a signal that is always at a high level in the mutually different 120-degree energization sections. ＵＬ , S ＶＬ , S ＷＬ are output from the signal generator 50 as PWM signals in mutually different 120-degree conduction sections.

[0044] In the first mode, as shown in FIG. ＵＨ , S ＶＨ , S ＷＨ As a result, the switching element 13 shown in FIG. １ , 13 ３ , 13 ５ is switched in a PWM cycle. １ , 13 ３ , 13 ５ Switching loss occurs in the switching element 13 １ , 13 ３ , 13 ５ The diode 14 generates heat. １ , 14 ３ , 14 ５ Reverse recovery loss occurs at 14 １ , 14 ３ , 14 ５ develops a fever.

[0045] Switching element 13 １ , 13 ３ , 13 ５ If the switching element 13 overheats, １ , 13 ３ , 13 ５ This may result in a decrease in the characteristics, shortened lifespan, or breakdown of the diode 14. １ , 14 ３ , 14 ５ If the diode 14 overheats, １ , 14 ３ , 14 ５ This may result in a decrease in the characteristics, shortened lifespan, or failure.

[0046] On the other hand, the switching element 13 ２ , 13 ４ , 13 ６ Since the switching element 13 is not PWM controlled, ２ , 13 ４ , 13 ６ In the case of the diode 14, no switching loss occurs due to PWM control. ２ , 14 ４ , 14 ６ In this case, no reverse recovery loss occurs due to PWM control.

[0047] In the second mode, as shown in FIG. ＵＬ , S ＶＬ , S ＷＬ As a result, the switching element 13 shown in FIG. ２ , 13 ４ , 13 ６ is switched in a PWM cycle. ２ , 13 ４ , 13 ６ Switching loss occurs in the switching element 13 ２ , 13 ４ , 13 ６ The diode 14 generates heat. ２ , 14 ４ , 14 ６ Reverse recovery loss occurs at 14 ２ , 14 ４ , 14 ６ develops a fever.

[0048] Switching element 13 ２ , 13 ４ , 13 ６ If the switching element 13 overheats, ２ , 13 ４ , 13 ６ This may result in a decrease in the characteristics, shortened lifespan, or breakdown of the diode 14. ２ , 14 ４ , 14 ６ If the diode 14 overheats, ２ , 14 ４ , 14 ６ This may result in a decrease in the characteristics, shortened lifespan, or failure.

[0049] On the other hand, the switching element 13 １ , 13 ３ , 13 ５ Since the switching element 13 is not PWM controlled, １ , 13 ３ , 13 ５ In the case of the diode 14, no switching loss occurs due to PWM control. １ , 14 ３ , 14 ５ In this case, no reverse recovery loss occurs due to PWM control.

[0050] In this way, in the 120-degree conduction method, when the power converter 10 is controlled in the first mode, heat is generated in the upper arm 11 due to PWM control, and when the power converter 10 is controlled in the second mode, heat is generated in the lower arm 12 due to PWM control.

[0051] Therefore, the switching unit 52 switches between a first mode in which the upper arm 11 is PWM-controlled and a second mode in which the lower arm 12 is PWM-controlled under predetermined conditions. The switching unit 52 switches the drive mode by, for example, outputting a drive mode command indicating the type of drive mode from the switching unit 52 to the switching element control unit 51. The switching element control unit 51 controls the power converter 10 in the drive mode indicated by the latest drive mode command output from the switching unit 52.

[0052] In this way, the signal generator 50 switches between the first mode and the second mode to control the power converter 10. As a result, the signal generator 50 can distribute the heat generated by PWM control to the upper arm 11 and the lower arm 12, preventing heating on only one side, thereby improving the reliability of the power conversion device 5.

[0053] The predetermined conditions include, for example, a predetermined time condition and a predetermined temperature condition. The predetermined temperature conditions include, for example, a first temperature condition and a second temperature condition. The process of the switching unit 52 will be described in detail below.

[0054] <2.3.1. Switching Process Based on Time Condition> FIG. 5 is a diagram for explaining switching of the drive mode based on a predetermined time condition by the switching unit 52 in the signal generator 50 of the power conversion device 5 according to this embodiment.

[0055] 5 , the switching unit 52 controls the switching element control unit 51 based on a predetermined time condition, and switches between a first mode in which the upper arm 11 is PWM controlled and a second mode in which the lower arm 12 is PWM controlled. The PWM control of the upper arm 11 is performed by PWM controlling the switching element 13 of the upper arm 11, and the PWM control of the lower arm 12 is performed by PWM controlling the switching element 13 of the lower arm 12.

[0056] For example, the switching unit 52 may select the first mode as the first time U １ If the above condition continues for more than the first time period U, the control of the power converter 10 is switched from the first mode to the second mode. ２ If this continues, the control of the power converter 10 is switched from the second mode to the first mode.

[0057] In this way, by switching between the first mode and the second mode, heating due to switching losses and the like can be distributed to the upper arm 11 and the lower arm 12, thereby improving the reliability of the power converter 10.

[0058] Also, depending on the configuration of the power converter 10, the first time U １ and the second time U ２ By appropriately setting the time ratio, the first mode and the second mode can be switched at a time ratio according to the configuration of the power converter 10, thereby further improving the reliability of the power converter 10.

[0059] 1st Hour U １ is set to n1 times the PWM period, and the second time U ２ is set to n2 times the PWM period, where n1 and n2 are, for example, integers equal to or greater than 1. This allows the power conversion device 5 to achieve precise temporal suppression of temperature rise.

[0060] Also, the first time U １ is set to m1 times the electrical angle period, and the second time U ２ may be set to m2 times the electrical angle period. m1 and m2 are, for example, integers equal to or greater than 1. This makes it possible to suppress the temperature rise in units of electrical angle periods.１ and the second time U ２ may be a value in units of seconds, which allows the temperature rise to be suppressed in units of several seconds.

[0061] Here, it is assumed that, due to reasons such as the configuration or arrangement of the power converter 10, the upper arm 11 of the upper arm 11 and the lower arm 12 of the power converter 10 is more likely to generate heat. １ is set to 200 μS, and the second time U ２ In this case, the first mode continues for 200 μs, and then the second mode continues for 300 μs, and this state is repeated.

[0062] Therefore, the low-side switching period during which the lower arm 12 is PWM controlled is longer than the high-side switching period during which the upper arm 11 is PWM controlled, which makes it possible to suppress heat generation in the upper arm 11 and to achieve a well-balanced control of the temperature rise of the upper arm 11 and the temperature rise of the lower arm 12.

[0063] The signal generator 50 is configured to insert dead time when switching between drive modes, thereby suppressing the occurrence of through current, but the signal generator 50 does not have to be configured to insert dead time when switching between drive modes.

[0064] For example, instead of inserting dead time, the signal generator 50 has a process for setting the timing for switching the drive mode to a specific timing, and by such a process, the occurrence of through current in the power converter 10 can be suppressed.

[0065] The signal generator 50 generates the gate signal S ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ The signal generator 50 switches the drive mode at a timing when the state of the power converter 10 does not change.

[0066] For example, when the signal generator 50 is configured to generate a signal for PWM control using a carrier wave having the same period as the PWM period, the drive mode is switched at the timing of the peak of the carrier wave. ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ The drive mode is switched at a timing when the state of

[0067] 6 is a diagram for explaining the timing of switching the drive mode by the switching unit 52 in the signal generator 50 of the power conversion device 5 according to the embodiment. In the example shown in FIG. 6, the gate signal S before and after switching the drive mode from the first mode to the second mode at an electrical angle of approximately 50 degrees is ＵＨ , S ＵＬ , S ＶＨ , S ＶＬ The state of the carrier wave is shown.

[0068] In the example shown in FIG. 6A, the first mode is switched to the second mode at the timing of the trough of the carrier wave, and the gate signal S ＵＨ , S ＵＬ , S ＶＨ , S ＶＬ Among them, the gate signal S ＵＨ , S ＶＬ Therefore, there is a risk of a shoot-through current occurring in the power converter 10.

[0069] On the other hand, in the example shown in FIG. 6B, the first mode is switched to the second mode at the timing of the peak of the carrier wave, and the gate signal S ＵＨ , S ＵＬ , S ＶＨ , S ＶＬ Therefore, no through current occurs in the power converter 10.

[0070] In this way, the signal generator 50 generates the gate signal S ＵＨ , S ＶＨ , S ＷＨ , SＵＬ , S ＶＬ , S ＷＬ The occurrence of through current can be suppressed by switching the drive mode at a timing that does not change the state of the drive mode. The timing of switching the drive mode is the same when switching the drive mode based on temperature conditions, which will be described later.

[0071] FIG. 7 is a flowchart showing an example of a process of switching the drive mode based on a predetermined time condition by the switching unit 52 in the signal generator 50 of the power conversion device 5 according to the embodiment.

[0072] The process shown in Fig. 7 is an interrupt process, and is repeatedly executed in synchronization with, for example, the PWM period. When the process shown in Fig. 7 is executed for the first time, all of the arms 11 and 12 are in the OFF state, but this is not limiting.

[0073] As shown in FIG. 7, the switching unit 52 １ in unit time Δ ｔ１ (Step S10). The switching unit 52 adds the time t １ is the time threshold u １ It is determined whether the time threshold u is equal to or less than the threshold (step S11). １ is the first time U １ This is an example.

[0074] The switching unit 52 is １ is the time threshold u １ If it is determined that the current is equal to or less than the predetermined value (step S11: Yes), the driving mode of the power converter 10 by the switching element control unit 51 is set to the first mode (step S12).

[0075] In step S12, the switching unit 52 outputs a drive mode command including information indicating the first mode to the switching element control unit 51. As a result, the switching element control unit 51 drives the power converter 10 in the first mode.

[0076] Furthermore, the switching unit 52 １ is the time threshold u １If it is determined that the value is not equal to or greater than the predetermined value (step S11: No), the drive mode of the power converter 10 by the switching element control unit 51 is set to the second mode (step S13).

[0077] In step S13, the switching unit 52 outputs a drive mode command including information indicating the second mode to the switching element control unit 51. As a result, the switching element control unit 51 drives the power converter 10 in the second mode.

[0078] When the process of step S13 is completed, the switching unit 52 １ is the time threshold u ２ It is determined whether the time threshold u is less than the time threshold u (step S14). ２ and the time threshold u １ The difference Δu (= u ２ -u １ ) is the second time U ２ This is an example.

[0079] The switching unit 52 is １ is the time threshold u ２ If it is determined that the time t １ to 0 (step S15). The switching unit 52 resets the value of the time t １ is the time threshold u ２ If it is determined that the difference is less than the predetermined value (step S14: Yes), the process shown in FIG. 7 ends.

[0080] The switching unit 52 determines the first time U based on the electrical angular velocity of the motor 2. １ and the second time U ２ For example, the switching unit 52 may change the first time U １ and the second time U ２ While maintaining the ratio of １ and the second time U ２ The switching unit 52 can change the electrical angular velocity of the motor 2 based on, for example, a speed command value or a position θ ｅ It can be determined based on the following.

[0081] The switching unit 52 also detects the three-phase current value I ＵＶＷ Based on this, the first time U １ and the second time U ２ For example, the switching unit 52 may change the three-phase current value I ＵＶＷ and calculating an effective value of the phase current or a torque current (q-axis current) value based on the calculated effective value of the phase current or the torque current value. １ and the second time U ２ For example, the switching unit 52 changes the first time U １ and the second time U ２ While maintaining the ratio of １ and the second time U ２ and can be shortened.

[0082] The switching unit 52 detects the three-phase current value I ＵＶＷ Based on the estimated back electromotive force, a first time U １ and the second time U ２ For example, the switching unit 52 changes the first time U １ and the second time U ２ While maintaining the ratio of １ and the second time U ２ and can be shortened.

[0083] <2.3.2. Switching Process Based on First Temperature Condition> FIG. 8 is a diagram for explaining switching of the drive mode based on a predetermined first temperature condition by the switching unit 52 in the signal generator 50 of the power conversion device 5 according to this embodiment.

[0084] As shown in Figure 8, the switching unit 52 controls the switching element control unit 51 based on a predetermined first temperature condition, and switches between a first mode in which the upper arm 11 is PWM controlled and a second mode in which the lower arm 12 is PWM controlled.

[0085] The first temperature condition is the maximum temperature T Ｈｍａｘand the maximum temperature T of the lower arm 12 Ｌｍａｘ For example, the condition is related to the difference between the maximum temperature T Ｈｍａｘ and the maximum temperature T of the lower arm 12 Ｌｍａｘ The condition is that the difference between the

[0086] The maximum temperature T of the upper arm 11 Ｈｍａｘ is the three-phase upper arm 11 １ , 11 ２ , 11 ３ The maximum temperature T of the lower arm 12 is the temperature of the upper arm, which is the highest among the temperatures of the upper arm 12 and the lower arm 12. Ｌｍａｘ is the three-phase lower arm 12 １ , 12 ２ , 12 ３ The temperature of the lower arm is the highest among the temperatures of the upper and lower arms.

[0087] The switching unit 52 is a temperature sensor 15 １ , 15 ３ , 15 ５ The temperature Td output from １ , Td ３ , Td ５ The highest temperature among these is the maximum temperature T Ｈｍａｘ The switching unit 52 also determines whether the temperature sensor 15 ２ , 15 ４ , 15 ６ The temperature Td output from ２ , Td ４ , Td ６ The highest temperature among these is the maximum temperature T Ｌｍａｘ It is judged as follows.

[0088] The switching unit 52 detects the maximum temperature T Ｈｍａｘ The maximum temperature T of the lower arm 12 Ｌｍａｘ The temperature difference ΔT is the value obtained by subtracting ＨＬｍａｘ The switching unit 52 calculates the calculated temperature difference ΔT ＨＬｍａｘ is the temperature threshold T ４ When the temperature threshold T ４ is an example of the first threshold value.

[0089] The switching unit 52 also detects the maximum temperature T ＬｍａｘThe maximum temperature T of the upper arm 11 Ｈｍａｘ The temperature difference ΔT is the value obtained by subtracting ＬＨｍａｘ The switching unit 52 calculates the calculated temperature difference ΔT ＬＨｍａｘ is the temperature threshold T ３ When the temperature threshold T is reached, the drive mode of the power converter 10 is switched from the second mode to the first mode. ３ is an example of the second threshold value.

[0090] In addition, the switching unit 52 is connected to the upper arm 11 １ , 11 ２ , 11 ３ and the lower arm 12 １ , 12 ２ , 12 ３ The temperature of the arm with the highest temperature is the maximum temperature T ｍａｘ The switching unit 52 determines the maximum temperature T ｍａｘ is the temperature threshold T １ If this occurs, a control stop command is output to the switching element control unit 51.

[0091] When a control stop command is output from the switching unit 52, the switching element control unit 51 stops the gate signal S ＵＨ , S ＶＨ , S ＷＨ , S ＵＬ , S ＶＬ , S ＷＬ Therefore, in the power converter 10, all of the arms 11 and 12 are turned off, and heat generation in all of the arms 11 and 12 is stopped. This allows the signal generator 50 to suppress breakdowns and the like in the power converter 10.

[0092] After the switching unit 52 shifts the switching element control unit 51 to the control stop mode, the switching unit 52 ｍａｘ is the temperature threshold T ２ If the temperature becomes less than the threshold temperature T ２ is the temperature threshold T １When a control start command is output from the switching unit 52, the switching element control unit 51 cancels the control stop mode and drives the power converter 10 while switching between the first mode and the second mode.

[0093] For example, the temperature threshold T １ is 160°C, and the temperature threshold T ２ is 150° C., and the initial temperatures of the arms 11 and 12 are 25° C. The signal generator 50 drives the power converter 10 alternately between the first mode and the second mode, thereby increasing the temperatures of the upper arm 11 and the lower arm 12.

[0094] The maximum temperature T of the upper arm 11 and the lower arm 12 ｍａｘ is the temperature threshold T １ When the temperature reaches 160°C, the control mode is switched to the control stop mode, and all the arms 11 and 12 are turned off, so that the temperatures of all the arms 11 and 12 decrease. Then, the temperatures of the upper arm 11 and the lower arm 12 decrease, and the maximum temperature T ｍａｘ is the temperature threshold T ２ Even if the temperature falls below 160°C, the control stop mode continues. ｍａｘ is the temperature threshold T ２ = 150°C, the signal generator 50 resumes driving the power converter 10 in the first mode or the second mode.

[0095] Here, the temperature threshold T １ = temperature threshold T ２ = 160°C. In this case, the maximum temperature T ｍａｘ is the temperature threshold T ２ = 160°C, the signal generator 50 resumes driving the power converter 10 in the first mode or the second mode. Therefore, the temperature of the upper arm 11 or the lower arm 12 rises again, and the maximum temperature T ｍａｘ is the temperature threshold T １ = 160°C, causing a chattering phenomenon in which the power converter 10 repeatedly stops and restarts driving in a short time. １ , T ２ are set to values ​​of different magnitudes, which prevents the chattering phenomenon described above.

[0096] Similarly, the switching unit 52 switches the temperature threshold T ３ , T ４ are also set to different magnitude values, which prevents the phenomenon of switching between the first mode and the second mode in a short time.

[0097] FIG. 9 is a flowchart showing an example of a process of switching the drive mode based on a predetermined first temperature condition by the switching unit 52 in the signal generator 50 of the power conversion device 5 according to the embodiment.

[0098] The process shown in Fig. 9 is an interrupt process, and is repeatedly executed in synchronization with, for example, the PWM period. When the process shown in Fig. 9 is executed for the first time, all of the arms 11 and 12 are in the OFF state, but this is not limiting.

[0099] As shown in FIG. 9, the switching unit 52 determines whether the operation mode of the switching element control unit 51 is a control stop mode in which all the arms 11 and 12 are in an off state (step S20).

[0100] When the switching unit 52 determines that the control stop mode is selected (step S20: Yes), the maximum temperature T ｍａｘ is the temperature threshold T ２ The switching unit 52 determines whether the maximum temperature T ｍａｘ is the temperature threshold T ２ If it is determined that the difference is not less than 1 / 2 (step S21: No), the switching unit 52 causes the switching element control unit 51 to execute a process of controlling all of the arms 11, 12 to the OFF state (step S22). The process of step S22 is a control stop mode process. In step S22, the switching unit 52 causes the switching element control unit 51 to execute a process of controlling all of the arms 11, 12 to the OFF state, for example, by outputting a control stop command to the switching element control unit 51.

[0101] If the switching unit 52 determines that the control stop mode is not selected (step S20: No), the maximum temperature T ｍａｘ is the temperature threshold T １ The switching unit 52 determines whether the maximum temperature Tｍａｘ is the temperature threshold T １ If it is determined that the difference is not less than the predetermined value (step S23: No), the process of step S22 is executed.

[0102] The switching unit 52 is configured to ｍａｘ is the temperature threshold T ２ If it is determined that the temperature is less than the maximum temperature T ｍａｘ is the temperature threshold T １ If it is determined that the difference is less than the predetermined value (step S23: Yes), it is determined whether the drive mode of the power converter 10 is the second mode (step S24).

[0103] When the switching unit 52 determines that the drive mode of the power converter 10 is the second mode (step S24: Yes), the switching unit 52 ＬＨｍａｘ is the temperature threshold T ３ It is determined whether or not it is less than the predetermined value (step S25).

[0104] The switching unit 52 detects the temperature difference ΔT ＬＨｍａｘ is the temperature threshold T ３ If it is determined that the temperature difference ΔT is less than 100°C (step S25: Yes), the switching unit 52 sets the drive mode of the power converter 10 to the second mode (step S27). ＬＨｍａｘ is the temperature threshold T ３ If it is determined that the difference is not less than the predetermined value (step S25: No), the drive mode of the power converter 10 is set to the first mode (step S28).

[0105] When the switching unit 52 determines that the drive mode of the power converter 10 is not the second mode (step S24: No), the switching unit 52 ＨＬｍａｘ is the temperature threshold T ４ It is determined whether or not it is less than the predetermined value (step S26).

[0106] The switching unit 52 detects the temperature difference ΔT ＨＬｍａｘ is the temperature threshold T ４ If it is determined that the temperature difference ΔT is less than the predetermined value (step S26: Yes), the process of step S28 is executed. ＨＬｍａｘ is the temperature threshold T ４If it is determined that the difference is not less than the predetermined value (step S26: No), the process of step S27 is executed.

[0107] When the process of step S22 is completed, when the process of step S27 is completed, or when the process of step S28 is completed, the switching unit 52 ends the process shown in FIG.

[0108] In the above example, the switching unit 52 is configured to switch the maximum temperature T Ｈｍａｘ and the maximum temperature T of the lower arm 12 Ｌｍａｘ Although the drive mode of the power converter 10 is switched between the first mode and the second mode based on the difference between the first temperature condition and the second temperature condition, the first temperature condition is not limited to the above example.

[0109] For example, the switching unit 52 may be configured to Ｈｍａｘ and the maximum temperature T of the lower arm 12 Ｌｍａｘ Instead, the average temperature T of the upper arm 11 Ｈａｖｅ and the average temperature T of the lower arm 12 Ｌａｖｅ can also be used.

[0110] In this case, the switching unit 52 is turned on when the maximum temperature T Ｈｍａｘ and the maximum temperature T of the lower arm 12 Ｌｍａｘ For example, the switching unit 52 may change the drive mode of the power converter 10 by the same process as in the case of the average temperature T Ｈａｖｅ and the average temperature T of the three-phase lower arm 12 Ｌａｖｅ Based on the difference between the first and second modes, the drive mode of the power converter 10 is switched between the first mode and the second mode.

[0111] The switching unit 52 may be configured to, for example, change the average temperature T Ｈａｖｅ is the average temperature T of the lower arm 12 Ｌａｖｅ than the temperature threshold T ５ If the temperature threshold T ５ is an example of the third threshold value.

[0112] The switching unit 52 also detects the average temperature T Ｌａｖｅ is the average temperature T of the upper arm 11Ｈａｖｅ than the temperature threshold T ６ If the temperature threshold T ６ is an example of the fourth threshold value.

[0113] Average temperature T of the upper arm 11 Ｈａｖｅ upper arm 11 １ , 11 ２ , 11 ３ and the average temperature T Ｌａｖｅ is the lower arm 12 １ , 12 ２ , 12 ３ is the average temperature of

[0114] Average temperature T of the upper arm 11 Ｈａｖｅ and the average temperature T of the lower arm 12 Ｌａｖｅ is a simple average value, as shown in the following formulas (1) and (2). Ｈａｖｅ = (Td １ + Td ３ + Td ５ ) / 3...(1) T Ｌａｖｅ = (Td ２ + Td ４ + Td ６ ) / 3 ... (2)

[0115] In addition, the average temperature T Ｈａｖｅ and the average temperature T of the lower arm 12 Ｌａｖｅ may be a weighted average value as shown in the following equations (3) and (4). Ｈａｖｅ = (α1 × Td １ + β1 × Td ３ + γ1 × Td ５ ) / 3...(3) T Ｌａｖｅ = (α2 × Td ２ + β2 × Td ４ + γ2 × Td ６ ) / 3 ... (4)

[0116] In the above equations (3) and (4), the weights α1, β1, γ1, α2, β2, and γ2 are determined based on experimental results or analysis results during the development of the power conversion device 5, but may also be determined based on the actual temperature rise observed when the power conversion device 5 is checked for operation after shipment.

[0117] For example, the upper arm 11 １ , 11 ２ , 11 ３ The weights α1, β1, and γ1 of the upper arm 11, which is more likely to be heated, are set to have a larger value, and the weight of the lower arm 12 １ , 12 ２ , 12 ３ Among the weights α1, β1, γ1, α2, β2, and γ2, the weight of the lower arm 12 that is more likely to increase in temperature is increased. The weights α1, β1, γ1, α2, β2, and γ2 can be set in the signal generator 50 via an interface (not shown) in the power conversion device 5, for example.

[0118] Furthermore, for example, when the highest temperature difference between the upper arms 11 is less than the threshold value, the switching unit 52 determines the average temperature T Ｈａｖｅ otherwise, the maximum temperature T Ｈｍａｘ Similarly, for example, when the highest temperature difference between the lower arms 12 is less than the threshold value, the switching unit 52 may use the average temperature T Ｌａｖｅ otherwise, the maximum temperature T Ｌｍａｘ can be used.

[0119] <2.3.3. Switching Process Based on Second Temperature Condition> The switching unit 52 switches the driving mode based on the second temperature condition when the temperature is the highest temperature T Ｈｍａｘ The temperature rise of the upper arm 11 is suppressed so that the temperature is kept at the maximum temperature T Ｌｍａｘ The first mode and the second mode are switched over so as to suppress the temperature rise of the lower arm 12 .

[0120] The switching unit 52 is Ｈｍａｘ The phase and temperature of the upper arm 11 are the maximum temperature T ＬｍａｘWhen the phase of the lower arm 12 matches the phase of the U-phase, the matching phase is designated as the X-phase, and switching between the first mode and the second mode is performed in the X-phase protection mode. The X-phase is any one of the U-phase, V-phase, and W-phase. There are three types of X-phase protection modes: the U-phase protection mode, the V-phase protection mode, and the W-phase protection mode, which are selected by the switching unit 52.

[0121] In the X-phase protection mode, the switching unit 52 switches between the first mode and the second mode so that the X-phase upper arm 11 and the X-phase lower arm 12 are not PWM controlled. Specifically, in the X-phase protection mode, the switching unit 52 sets the drive mode of the power converter 10 to the second mode during a current-carrying period of the X-phase upper arm 11. Furthermore, the switching unit 52 sets the drive mode of the power converter 10 to the first mode during a current-carrying period of the X-phase lower arm 12.

[0122] In this way, the switching unit 52 sets the drive mode to the second mode during the energization period of the X-phase upper arm 11 and the first mode during the energization period of the X-phase lower arm 12, thereby avoiding PWM control of the X-phase upper arm 11 and the X-phase lower arm 12. This allows the power conversion device 5 to suppress temperature increases in the X-phase upper arm 11 and the X-phase lower arm 12.

[0123] For example, the switching unit 52 Ｈｍａｘ The phase and temperature of the upper arm 11 are the maximum temperature T Ｌｍａｘ If the phase of the lower arm 12 is the same as the U phase, the first mode and the second mode are switched in the U phase protection mode.

[0124] In the U-phase protection mode, the switching unit 52 switches the upper arm 11 of the U-phase １ and the U-phase lower arm 12 １ Specifically, the switching unit 52 switches between the first mode and the second mode so that the upper arm 11 of the U phase is not PWM controlled. １ During the energization period, the drive mode is set to the second mode, and the lower arm 12 of the U phase １ During the energization period, the drive mode is set to the first mode, so that the upper arm 11 of the U phase １ and the U-phase lower arm 12 １Avoid PWM control.

[0125] 10 is a diagram for explaining the switching of the drive mode in the U-phase protection mode by the switching unit 52 in the signal generator 50 of the power conversion device 5 according to the embodiment. As shown in FIG. 10, the switching unit 52 switches the drive mode of the U-phase upper arm 11 in the U-phase protection mode. １ At the start of the energization period, the drive mode is switched to the second mode.

[0126] As shown in FIG. 10, in the U-phase protection mode, the switching unit 52 switches the U-phase lower arm 12 １ The drive mode is switched to the first mode at the start timing of the conduction period of the U-phase upper arm 11 in the power conversion device 5. １ and the U-phase lower arm 12 １ Therefore, PWM control can be avoided.

[0127] In addition, the upper arm 11 of the U phase １ During the conduction period, the power converter 10 is driven in the second mode, and the lower arm 12 of the U phase １ The timing of switching the drive mode is not limited to the above example, as long as the power converter 10 is driven in the first mode during the current-carrying period.

[0128] Furthermore, the switching unit 52 Ｈｍａｘ The phase and temperature of the upper arm 11 are the maximum temperature T Ｌｍａｘ When the phase of the lower arm 12 is different from that of the lower arm 12, X Ｈ Y Ｌ In the protection mode, the first mode and the second mode are switched. Ｈ is the maximum temperature T among the U, V, and W phases. Ｈｍａｘ The phase of the upper arm 11 is X Ｈ It may be written as Y phase. Ｌ is the maximum temperature T among the U, V, and W phases. Ｌｍａｘ The phase of the lower arm 12 is Y Ｌ It may be referred to as a phase.

[0129] X Ｈ Y Ｌ The protection mode is U Ｈ VＬ Protected Mode, U Ｈ W Ｌ Protected Mode, V Ｈ U Ｌ Protected Mode, V Ｈ W Ｌ Protected Mode, W Ｈ U Ｌ Protected Mode, W Ｈ V Ｌ There are six types of protection modes, which are selected by the switching unit 52.

[0130] For example, the switching unit 52 Ｈｍａｘ The phase of the upper arm 11 where the temperature is the maximum temperature T Ｌｍａｘ If the phase of the lower arm 12 is the V phase, then Ｈ V Ｌ In the protection mode, the first mode and the second mode are switched.

[0131] The switching unit 52 is Ｈ V Ｌ In protection mode, the maximum temperature T Ｈｍａｘ During at least a part of the energization period of the upper arm 11, the drive mode is set to the second mode, and the maximum temperature T Ｌｍａｘ The drive mode is set to the first mode for at least a part of the current-carrying period of the lower arm 12.

[0132] X Ｈ the conduction period of the upper arm 11 of the Y phase, Ｌ The current conduction period of the lower arm 12 of the X phase overlaps with the current conduction period of the lower arm 12 of the X phase by a period of 60 degrees. Ｈ The drive mode is set to the second mode during a 90-degree period of the energization period of the upper arm 11 of the Y phase, Ｌ The drive mode is set to the first mode during a 90-degree period of the current-carrying period of the lower arm 12 of the phase.

[0133] In this way, the switching unit 52 Ｈ During at least a part of the energization period of the upper arm 11 of the Y phase, the drive mode is set to the second mode, Ｌ By setting the drive mode to the first mode during at least a part of the current-carrying period of the lower arm 12 of the X phase, Ｈ Upper arm 11 of the Y phase ＬThis avoids PWM control with the lower arm 12 of the X phase. Ｈ Upper arm 11 of the Y phase Ｌ The temperature rise between the lower arm 12 and the phase can be suppressed.

[0134] FIG. 11 shows a U-phase signal generated by a switching unit 52 in a signal generator 50 of a power conversion device 5 according to an embodiment. Ｈ V Ｌ 11 is a diagram for explaining switching of the drive mode in the protection mode. As shown in FIG. Ｈ V Ｌ In the protection mode, the upper arm 11 of the U phase １ and the V-phase lower arm 12 １ During the overlapping period with the current-carrying period, the driving mode is switched from the first mode to the second mode.

[0135] FIG. 12 is a flowchart showing an example of a process of switching the drive mode based on a predetermined second temperature condition by the switching unit 52 in the signal generator 50 of the power conversion device 5 according to the embodiment.

[0136] The process shown in Fig. 12 is an interrupt process, and is executed repeatedly in synchronization with, for example, a PWM period. When the process shown in Fig. 12 is executed for the first time, the protection modes are U-phase protection mode, V-phase protection mode, W-phase protection mode, ... Ｈ V Ｌ Protected Mode, U Ｈ W Ｌ Protected Mode, V Ｈ U Ｌ Protected Mode, V Ｈ W Ｌ Protected Mode, W Ｈ U Ｌ Protected Mode, W Ｈ V Ｌ It is either in protected mode.

[0137] 12 is initially performed in a protection mode that corresponds to the configuration of the power converter 10. For example, if the flow path of the cooling water flowing through a cooling device (not shown) provided in the power converter 10 is configured in the order of U phase → V phase → W phase, the phase furthest downstream from the cooling device (not shown) is most likely to increase in temperature, and therefore the protection mode that is initially performed is the W-phase protection mode.

[0138] As shown in FIG. 12, the switching unit 52 ２ is the time threshold u ３ The switching unit 52 determines whether the time t ２ is the time threshold u ３ If it is determined that the temperature is equal to or higher than the maximum temperature T Ｈｍａｘ and the maximum temperature T of the lower arm 12 Ｌｍａｘ It is determined (step S31).

[0139] The switching unit 52 is configured to Ｈｍａｘ The upper arm 11 and the maximum temperature T Ｌｍａｘ The switching unit 52 determines whether the upper arm 12 and the lower arm 12 are in the same phase (step S32). Ｈｍａｘ The upper arm 11 and the maximum temperature T Ｌｍａｘ If it is determined that the upper arm 11 and the lower arm 12 of the X phase are of the same phase (step S32: Yes), control is performed in the X-phase protection mode (step S33). In the X-phase protection mode, the drive mode of the power converter 10 is set to the second mode during the energization period of the upper arm 11 of the X phase, and the drive mode of the power converter 10 is set to the first mode during the energization period of the lower arm 12 of the X phase.

[0140] The switching unit 52 also detects the maximum temperature T Ｈｍａｘ The upper arm 11 and the maximum temperature T Ｌｍａｘ If it is determined that the lower arm 12 of X is not of the same phase (step S32: No), Ｈ Y Ｌ Control is performed in the protection mode (step S34). Ｈ Y Ｌ Control in protected mode is X Ｈthe drive mode of the power converter 10 is set to the second mode during at least a part of the current-carrying period of the upper arm 11 of the Y phase; Ｌ This control sets the drive mode of the power converter 10 to the first mode for at least a part of the current-carrying period of the lower arm 12 of the phase.

[0141] When the process of step S33 is completed or when the process of step S34 is completed, the switching unit 52 determines whether or not the protection mode is to be switched (step S35). When the switching unit 52 determines that the protection mode is to be switched (step S35: Yes), the switching unit 52 ２ to 0 (step S36). ２ is the time threshold u ３ If it is determined that the number is not equal to or greater than the limit (step S30: No), the current protection mode is maintained (step S37).

[0142] When the process of step S36 is completed, when it is determined that the protection mode has not been switched (step S35: No), or when the process of step S37 is completed, the switching unit 52 ２ in unit time Δt ２ (step S38), and the process of FIG. 12 ends.

[0143] As shown in FIG. 12, the switching unit 52 ２ is the time threshold u ３ By determining whether or not the above condition is met, it is possible to prevent chattering, in which the protection mode is switched in a short time, and to stably drive the power converter 10. Furthermore, the process shown in Fig. 12 has fewer branches than the process shown in Fig. 9, and therefore it is possible to simplify program implementation and reduce the processing load, for example.

[0144] Furthermore, since the switching unit 52 switches the protection mode depending on the temperature state of the arms 11 and 12, it is possible to prevent overheating of a specific arm, thereby improving the reliability of the power converter 10.

[0145] The switching unit 52 is X ＨThe period during which the upper arm 11 of the Y phase is energized in the second mode and the period during which the upper arm 11 of the Y phase is energized in the second mode Ｌ The ratio of the period during which the lower arm 12 of the phase is energized to the period during which the first mode is set is set to the maximum temperature T Ｈｍａｘ and the maximum temperature T of the lower arm 12 Ｌｍａｘ The ratio can be set according to the difference between

[0146] For example, the switching unit 52 may be configured to Ｈｍａｘ is the maximum temperature T of the lower arm 12 Ｌｍａｘ If higher than X Ｈ The period during which the upper arm 11 of the Y phase is energized in the second mode is Ｌ The conduction period of the lower arm 12 of the phase can be made longer than the period in which the first mode is set. Ｈｍａｘ and the maximum temperature T of the lower arm 12 Ｌｍａｘ It is possible to switch between appropriate modes depending on the situation.

[0147] The switching unit 52 may be configured to, for example, Ｈｍａｘ is the maximum temperature T Ｌｍａｘ The higher the Ｈ The period during which the upper arm 11 of the Y phase is energized in the second mode is Ｌ The conduction period of the lower arm 12 of the phase can be made longer than the period in which the first mode is set.

[0148] Similarly, the switching unit 52 is Ｈｍａｘ is the maximum temperature T Ｌｍａｘ If it is lower than Ｈ The period during which the upper arm 11 of the Y phase is energized in the second mode is Ｌ The conduction period of the lower arm 12 of the phase can be made shorter than the period during which the first mode is set. Ｈｍａｘ and the maximum temperature T of the lower arm 12 Ｌｍａｘ It is possible to switch between appropriate modes depending on the situation.

[0149] For example, the switching unit 52 may be configured to Ｈｍａｘ is the maximum temperature T Ｌｍａｘ The lower the ＨThe period during which the upper arm 11 of the Y phase is energized in the second mode is Ｌ The conduction period of the lower arm 12 of the phase can be made shorter than the period during which the first mode is set.

[0150] <2.3.4. Others> In the above example, an example where the current-carrying period is 120 degrees has been described. However, the signal generator 50 can also perform processing similar to that when the current-carrying period is 120 degrees, for example, when the current-carrying period is 150 degrees or 180 degrees.

[0151] 13 is a diagram for explaining the switching of the drive mode based on a predetermined time condition by the switching unit 52 when the current conduction period is 150 degrees in the power conversion device 5 according to this embodiment. As shown in FIG. 13 , when the current conduction period is 150 degrees, the switching unit 52 can switch the drive mode between the first mode and the second mode based on the predetermined time condition.

[0152] 14 is a diagram for explaining the switching of the drive mode based on a predetermined time condition by the switching unit 52 when the current conduction period is 180 degrees in the power conversion device 5 according to this embodiment. As shown in FIG. 14 , when the current conduction period is 180 degrees, the switching unit 52 can switch the drive mode between the first mode and the second mode based on the predetermined time condition.

[0153] The signal generator 50 may have a conduction period of 120 degrees or more and 180 degrees or less, and may have a period other than 120 degrees, 150 degrees, and 180 degrees, and is not limited to the above-mentioned example.

[0154] In the above example, the switching unit 52 uses the temperature Td detected by the temperature sensor 15 as is, but the present invention is not limited to this example. For example, the switching unit 52 can perform the above-described processing by using an estimated value such as the junction temperature of the switching element 13 estimated from the temperature Td detected by the temperature sensor 15 as the temperature of the switching element 13.

[0155] In addition, in the above example, the power conversion device 5 detects the temperature of each arm 11, 12 using the temperature sensor 15, but it may also be configured to have a temperature estimation unit that estimates the temperature of some or all of the arms 11, 12.

[0156] For example, the power conversion device 5 may be configured to include a temperature estimating unit (not shown) in the signal generator 50, instead of the temperature sensor 15, that estimates the temperatures of the arms 11 and 12. In this case, the temperature estimating unit may estimate, for example, the three-phase current value I ＵＶＷ The temperature of each arm 11, 12 is estimated based on the PWM period and the like, but the present invention is not limited to this example, and the temperature of each arm 11, 12 can be estimated by various estimation methods.

[0157] The power conversion device 5 may also be configured such that some of the six temperature sensors 15 described above are provided, but the remaining temperature sensors are not provided. In this case, the power conversion device 5 is provided with a temperature estimating unit (not shown) that estimates the temperatures of arms that do not have temperature sensors based on the temperatures detected by some of the temperature sensors 15. Note that this temperature estimating unit may estimate the three-phase current value I in addition to or instead of the temperatures detected by some of the temperature sensors 15. ＵＶＷ , the temperature may be estimated based on the PWM period or the like.

[0158] Furthermore, when one of the upper arm 11 and the lower arm 12 is PWM-controlled, the signal generator 50 can also PWM-control the other arm in a complementary manner, thereby suppressing heat generation due to diode conduction and preventing overheating, and improving the efficiency of the power converter 10.

[0159] The signal generator 50 can also switch between a first process in which the drive mode is set to a three-phase conduction mode and a second process in which the drive mode is switched between the first mode and the second mode. The three-phase conduction mode is, for example, a mode in which three-phase modulation is performed. For example, the switching unit 52 can ｍａｘ If the threshold value is less than the threshold value, the first process is executed, and the maximum temperature T ｍａｘis equal to or greater than the threshold value, the second process is executed. This allows the power conversion device 5 to perform driving that achieves both suppression of noise vibration and harshness (NVH) and suppression of temperature rise, for example.

[0160] The switching unit 52 can also select and execute the predetermined condition from a time condition, a first temperature condition, and a second temperature condition. For example, the switching unit 52 can switch between the time condition, the first temperature condition, and the second temperature condition as the predetermined condition depending on the speed or torque current (q-axis current) of the motor 2.

[0161] In the above example, the time condition, the first temperature condition, and the second temperature condition are described separately as the predetermined conditions, but the time condition and the temperature condition may be combined. ｍａｘ is the temperature threshold T ５ If the temperature is less than the maximum temperature T ｍａｘ is the temperature threshold T ５ If this is the case, the first mode and the second mode can be switched based on the first temperature condition or the second temperature condition.

[0162] 3. Hardware Configuration FIG. 15 is a diagram illustrating an example of the hardware configuration of the signal generator 50 of the power conversion device 5 according to the embodiment.

[0163] 15, the signal generator 50 includes a processor 90, a memory 91, an input / output interface (I / F) 92, and a media interface (I / F) 93. The processor 90, the memory 91, the input / output interface 92, and the media interface 93 are connected by a bus 95.

[0164] The processor 90 includes, for example, one or more of a central processing unit (CPU), a micro processing unit (MPU), a graphics processing unit (GPU), and a system large scale integration (LSI). The memory 91 is a random access memory (RAM) such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), or a semiconductor memory element.

[0165] The processor 90 transmits and receives information to and from an output device (not shown) and an input device (not shown) via the input / output interface 92. The processor 90 acquires data from the input device via the input / output interface 92. The processor 90 also outputs generated data to the output device via the input / output interface 92.

[0166] The media interface 93 reads a program or data stored in a recording medium 94 and provides the read data or program (an example of a drive program) to the processor 90 via the memory 91. The processor 90 loads the program from the recording medium 94 onto the memory 91 via the media interface 93 and executes the loaded program. The recording medium 94 is, for example, an optical recording medium such as a DVD (Digital Versatile Disc) or a PD (Phase Change Rewritable Disc), or a semiconductor memory.

[0167] The processor 90 executes a program using the memory 91 or the like as a working area, thereby realizing the functions of the switching element control unit 51 and the switching unit 52. Note that the signal generator 50 may be partially or entirely realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a DSP (Digital Signal Processor).

[0168] Although an embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

[0169] The present technology can be configured as follows: (1) A power conversion device including: a power converter having an upper arm and a lower arm for each of three phases; and a signal generator that generates signals to drive the upper arms and the lower arms of the three phases in the power converter using a current conduction method having a current conduction period of 120 degrees or more and 180 degrees or less, the current conduction method being to PWM-control one of the upper arms and the lower arms, wherein the signal generator includes a switching unit that switches, under predetermined conditions, a drive mode of the power converter between a first mode in which the upper arms are PWM-controlled and a second mode in which the lower arms are PWM-controlled. (2) The power conversion device according to (1), wherein the predetermined conditions include a predetermined time condition, and the switching unit switches the drive mode between the first mode and the second mode based on the predetermined time condition. (3) The power conversion device according to (2), wherein the switching unit switches the drive mode from the first mode to the second mode when the first mode has continued for a first time or more, and switches the drive mode from the second mode to the first mode when the second mode has continued for a second time or more. (4) The power conversion device according to any one of (1) to (3), wherein the predetermined condition includes a predetermined temperature condition, and the switching unit switches the drive mode between the first mode and the second mode based on the predetermined temperature condition. (5) The power conversion device according to (4), wherein the switching unit switches the drive mode between the first mode and the second mode based on a difference between a maximum temperature of the upper arm, which is the highest among temperatures of the three-phase upper arms, and a maximum temperature of the lower arm, which is the highest among temperatures of the three-phase lower arms. (6) The power conversion device according to (5), wherein the switching unit switches the drive mode from the first mode to the second mode when the maximum temperature of the upper arm becomes higher than the maximum temperature of the lower arm by a first threshold or more, and switches the drive mode from the second mode to the first mode when the maximum temperature of the lower arm becomes higher than the maximum temperature of the upper arm by a second threshold or more.(7) The power conversion device according to any one of (4) to (6), wherein the switching unit switches the drive mode between the first mode and the second mode based on a difference between an average temperature of the upper arm of the three phases and an average temperature of the lower arm of the three phases. (8) The power conversion device according to (7), wherein the switching unit switches the drive mode from the first mode to the second mode when the average temperature of the upper arm becomes higher than the average temperature of the lower arm by a third threshold or more, and switches the drive mode from the second mode to the first mode when the average temperature of the lower arm becomes higher than the average temperature of the upper arm by a fourth threshold or more. (9) The power conversion device according to any one of (4) to (8), wherein the switching unit sets the drive mode to the second mode during at least a portion of a current-carrying period of an upper arm having the highest temperature among the upper arms of the three phases. (10) The power conversion device according to any one of (4) to (9), wherein the switching unit sets the drive mode to the first mode during at least a portion of a current-carrying period of the lower arm having the highest temperature among the lower arms of the three phases. (11) The power conversion device according to any one of (4) to (10), wherein the switching unit switches the drive mode to a controlled stop mode in which all of the upper arms and the lower arms of the three phases are turned off when the highest temperature among the temperatures of the upper arms and the lower arms of the three phases becomes equal to or higher than a threshold. (12) A motor module comprising: a motor; and the power conversion device according to any one of (1) to (11), which supplies power to the motor.

[0170] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

Claims

1. A power conversion device comprising: a power converter having an upper arm and a lower arm for each of three phases; and a signal generator that generates signals to drive the upper arms and the lower arms of the three phases in the power converter using a current supply method having a current supply period of 120 degrees or more and 180 degrees or less, the current supply method being a current supply method in which one of the upper arms and the lower arms is PWM controlled, wherein the signal generator has a switching unit that switches, under predetermined conditions, the drive mode of the power converter between a first mode in which the upper arms are PWM controlled and a second mode in which the lower arms are PWM controlled.

2. The power conversion device according to claim 1, wherein the predetermined conditions include predetermined time conditions, and the switching unit switches the drive mode between the first mode and the second mode based on the predetermined time conditions.

3. The power conversion device according to claim 2, wherein the switching unit switches the drive mode from the first mode to the second mode when the first mode has continued for a first time or more, and switches the drive mode from the second mode to the first mode when the second mode has continued for a second time or more.

4. The power conversion device according to claim 1, wherein the predetermined conditions include predetermined temperature conditions, and the switching unit switches the drive mode between the first mode and the second mode based on the predetermined temperature conditions.

5. The power conversion device according to claim 4, wherein the switching unit switches between the first mode and the second mode as the drive mode based on the difference between the maximum temperature of the upper arm, which is the highest temperature among the temperatures of the upper arms of the three phases, and the maximum temperature of the lower arm, which is the highest temperature among the temperatures of the lower arms of the three phases.

6. The power conversion device described in claim 5, wherein the switching unit switches the drive mode from the first mode to the second mode when the maximum temperature of the upper arm becomes higher than the maximum temperature of the lower arm by a first threshold or more, and switches the drive mode from the second mode to the first mode when the maximum temperature of the lower arm becomes higher than the maximum temperature of the upper arm by a second threshold or more.

7. The power conversion device according to claim 4, wherein the switching unit switches the drive mode between the first mode and the second mode based on the difference between the average temperature of the upper arm of the three phases and the average temperature of the lower arm of the three phases.

8. The power conversion device described in claim 7, wherein the switching unit switches the drive mode from the first mode to the second mode when the average temperature of the upper arm becomes higher than the average temperature of the lower arm by a third threshold value or more, and switches the drive mode from the second mode to the first mode when the average temperature of the lower arm becomes higher than the average temperature of the upper arm by a fourth threshold value or more.

9. The power conversion device according to claim 4, wherein the switching unit sets the drive mode to the second mode during at least a portion of a current-carrying period of the upper arm having the highest temperature among the upper arms of the three phases.

10. The power conversion device according to claim 4, wherein the switching unit sets the drive mode to the first mode during at least a portion of a current-carrying period of the lower arm having the highest temperature among the three-phase lower arms.

11. A power conversion device as described in any one of claims 4 to 10, wherein the switching unit switches the drive mode to a controlled stop mode in which all of the upper arms and lower arms of the three phases are turned off when the highest temperature among the temperatures of the upper arms and the lower arms of the three phases becomes equal to or higher than a threshold value.

12. A motor module comprising: a motor; and a power conversion device according to any one of claims 1 to 10, which supplies power to the motor.

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