WO2019069919A1

WO2019069919A1 - Power conversion device, motor module, and electric power steering apparatus

Info

Publication number: WO2019069919A1
Application number: PCT/JP2018/036873
Authority: WO
Inventors: 弘光大橋; 香織鍋師
Original assignee: 日本電産株式会社
Priority date: 2017-10-06
Filing date: 2018-10-02
Publication date: 2019-04-11
Also published as: CN111164874A

Abstract

This power conversion device converts power supplied from a power source to power to be supplied to a motor having n-phase (n is an integer of 3 or greater) winding. The power conversion device is provided with a first inverter that is connected to one end of the winding of each phase of the motor, and a second inverter that is connected to the other end of the winding of each phase of the motor. The power conversion device has a first driving mode of performing n-phase energization control using motor neutral points formed in one of the first and second inverters and the other inverter, and a second driving mode of performing n-1-phase energization control using both the first and second inverters. In abnormal control, switching between the first driving mode and the second driving mode is performed.

Description

Power converter, motor module and electric power steering apparatus

The present disclosure relates to a power conversion device, a motor module, and an electric power steering device that convert power from a power supply into electric power supplied to an electric motor.

2. Description of the Related Art In recent years, a machine-electric integrated motor has been developed, in which an electric motor (hereinafter simply referred to as "motor"), a power conversion device, and an electronic control unit (ECU) are integrated. Particularly in the automotive field, high quality assurance is required from the viewpoint of safety. Therefore, a redundant design is adopted that can continue safe operation even if part of the part fails. As an example of redundant design, it is considered to provide two power converters for one motor. As another example, it is considered to provide a backup microcontroller on the main microcontroller.

Patent Document 1 discloses a power conversion device that includes a control unit and two inverters, and converts power supplied to a three-phase motor. Each of the two inverters is connected to a power supply and a ground (hereinafter referred to as "GND"). One inverter is connected to one end of the three-phase winding of the motor, and the other inverter is connected to the other end of the three-phase winding. Each inverter comprises a bridge circuit composed of three legs, each of which includes a high side switch element and a low side switch element. The control unit switches motor control from normal control to abnormal control when it detects a failure of the switch element in the two inverters. In the present specification, “abnormal” mainly means failure of the switch element. Also, "control at normal time" means control in a state where all switch elements are normal, and "control at abnormal time" means control in a state where a failure occurs in a certain switch element.

JP 2014-192950 A

In the prior art described above, it has been required to improve the motor output in control at the time of abnormality.

Embodiments of the present disclosure provide a power converter that can improve motor output in control at the time of abnormality.

An exemplary power converter of the present disclosure is a power converter that converts power from a power source to power supplied to a motor having n-phase (n is an integer of 3 or more) windings, A first inverter connected to one end of the winding of each phase, and a second inverter connected to the other end of the winding of each phase, wherein one and the other of the first and second inverters are configured Has a first drive mode to perform n-phase energization control using the neutral point of the motor and a second drive mode to perform n-1 phase energization control using both the first and second inverters In the control at the time of abnormality, the first drive mode and the second drive mode are switched.

According to an exemplary embodiment of the present disclosure, a power conversion device capable of improving a motor output in abnormal control by switching the first and second drive modes, and a motor module including the power conversion device And the electric-power-steering apparatus provided with the said motor module is provided.

FIG. 1 is a circuit diagram showing a circuit configuration of an inverter unit 100 according to an exemplary embodiment 1. FIG. 2 is a block diagram illustrating a block configuration of a motor module 2000 according to an exemplary embodiment 1. FIG. 3 exemplifies a current waveform (sine wave) obtained by plotting current values flowing in the A-phase, B-phase, and C-phase windings of the motor 200 when the power conversion device 1000 is controlled according to three-phase energization control. Is a graph. FIG. 4 is a diagram for explaining the on / off state of another SW when the SW 121 L of the A-phase leg of the first inverter 120 fails. FIG. 5 is a diagram showing a TN curve representing the relationship between the rotational speed (rps) per unit time of the motor and the normalized torque T (N · m). FIG. 6 is a flowchart illustrating a control flow for switching between the first drive mode and the second drive mode according to the speed command value. FIG. 7 is a flowchart illustrating a control flow for switching between the first drive mode and the second drive mode in accordance with the torque command value. FIG. 8 is a schematic view showing a typical configuration of an electric power steering apparatus 3000 according to the present second embodiment.

Hereinafter, embodiments of a power conversion device, a motor module, and an electric power steering device of the present disclosure will be described in detail with reference to the accompanying drawings. However, in order to facilitate the understanding of the person skilled in the art, the following description may be omitted unnecessarily to avoid redundant description. For example, detailed description of already well-known matters and redundant description of substantially the same configuration may be omitted.

In the present specification, the implementation of the present disclosure will be exemplified taking a power conversion device that converts power from a power supply into power supplied to a three-phase motor having three-phase (A-phase, B-phase, C-phase) windings. The form will be described. However, a power conversion device that converts power from a power supply to power supplied to an n-phase motor having n-phase (n is an integer of 4 or more) windings such as four-phase or five-phase is also within the scope of the present disclosure. .

(Embodiment 1)

[1-1. Structure of inverter unit 100]

FIG. 1 schematically shows a circuit configuration of the inverter unit 100 of the power conversion device 1000 according to the present embodiment.

The inverter unit 100 typically includes a power shutoff circuit 110, a first inverter 120 and a second inverter 130. The inverter unit 100 can convert the power from the power supply 101 into the power to be supplied to the motor 200. For example, the inverter unit 100 can convert DC power into three-phase AC power which is pseudo sine waves of A-phase, B-phase and C-phase.

The motor 200 is, for example, a three-phase alternating current motor. The motor 200 includes an A-phase winding M1, a B-phase winding M2, and a C-phase winding M3, and is connected to the first inverter 120 and the second inverter 130. Specifically, the first inverter 120 is connected to one end of the winding of each phase of the motor 200, and the second inverter 130 is connected to the other end of the winding of each phase. In the present specification, “connection” between components (components) mainly means electrical connection, and further includes connection of components via another component or element.

The first inverter 120 has terminals A_L, B_L and C_L corresponding to the respective phases. The second inverter 130 has terminals A_R, B_R and C_R corresponding to the respective phases. The terminal A_L of the first inverter 120 is connected to one end of the A-phase winding M1, the terminal B_L is connected to one end of the B-phase winding M2, and the terminal C_L is connected to one end of the C-phase winding M3. Connected Similar to the first inverter 120, the terminal A_R of the second inverter 130 is connected to the other end of the A-phase winding M1, the terminal B_R is connected to the other end of the B-phase winding M2, and the terminal C_R is , C phase is connected to the other end of the winding M3. Thus, inverter unit 100 includes a full H-bridge circuit configured of H-bridges of A-phase, B-phase and C-phase. The motor connections are different from so-called Y connections and delta connections.

The power supply shutoff circuit 110 has first to

fourth switch elements

111, 112, 113 and 114. In the inverter unit 100, the first inverter 120 can be electrically connected to the power supply 101 and GND by the power shutoff circuit 110. The second inverter 130 can be electrically connected to the power supply 101 and GND by the power shutoff circuit 110. Specifically, the first switch element 111 switches connection / non-connection between the first inverter 120 and GND. The second switch element 112 switches connection / non-connection between the power supply 101 and the first inverter 120. The third switch element 113 switches connection / disconnection between the second inverter 130 and GND. The fourth switch element 114 switches connection / disconnection between the power supply 101 and the second inverter 130.

The on / off of the first to

fourth switch elements

111, 112, 113 and 114 may be controlled by, for example, a microcontroller or a dedicated driver. The first to

fourth switch elements

111, 112, 113 and 114 can block bidirectional current. As the first to

fourth switch elements

111, 112, 113 and 114, for example, semiconductor switches such as thyristors, analog switch ICs, or field effect transistors (typically MOSFETs) in which parasitic diodes are formed, or A mechanical relay or the like can be used. A combination of a diode and an insulated gate bipolar transistor (IGBT) may be used. In the drawings of this specification, MOSFETs are illustrated as the first to

fourth switch elements

111, 112, 113 and 114. Hereinafter, the first to

fourth switch elements

111, 112, 113 and 114 may be described as

SWs

111, 112, 113 and 114, respectively.

The SW 111 is arranged such that a forward current flows toward the first inverter 120 in an internal parasitic diode. The SW 112 is arranged such that forward current flows in the parasitic diode toward the power supply 101. The SW 113 is disposed such that a forward current flows to the second inverter 130 in the parasitic diode. The SW 114 is arranged such that forward current flows in the parasitic diode toward the power supply 101.

The power shutoff circuit 110 preferably further includes fifth and

sixth switch elements

115 and 116 for reverse connection protection, as shown. The fifth and

sixth switch elements

115, 116 are typically semiconductor switches of a MOSFET having parasitic diodes. The fifth switch element 115 is connected in series to the SW 112, and is disposed such that a forward current flows toward the first inverter 120 in the parasitic diode. The sixth switch element 116 is connected in series to the SW 114, and is disposed such that a forward current flows toward the second inverter 130 in the parasitic diode. Even when the power supply 101 is connected in the reverse direction, the reverse current can be cut off by the two switch elements for reverse connection protection.

The number of switch elements to be used is not limited to the illustrated example, and is appropriately determined in consideration of design specifications and the like. Particularly in the on-vehicle field, high quality assurance is required from the viewpoint of safety, so it is preferable to provide a plurality of switch elements used for each inverter.

The power supply 101 is, for example, a single power supply common to the first and

second inverters

120 and 130. The power supply 101 generates a predetermined power supply voltage (for example, 12 V). As a power supply, for example, a DC power supply is used. However, the power source may be an AC-DC converter or a DC-DC converter, or may be a battery (storage battery). Also, the power supply 101 may separately include a power supply for the first inverter 120 and a power supply for the second inverter 130.

A coil 102 is provided between the power supply 101 and the power shutoff circuit 110. The coil 102 functions as a noise filter, and smoothes high frequency noise included in the voltage waveform supplied to each inverter or high frequency noise generated in each inverter so as not to flow out to the power supply side.

A capacitor 103 is connected to the power supply line of each inverter. The capacitor 103 is a so-called bypass capacitor, which suppresses voltage ripple. The capacitor 103 is, for example, an electrolytic capacitor, and the capacity and the number to be used are appropriately determined depending on design specifications and the like.

The first inverter 120 comprises a bridge circuit having three legs. Each leg has a low side switch element and a high side switch element. The A-phase leg has a low side switch element 121L and a high side switch element 121H. The B-phase leg has a low side switch element 122L and a high side switch element 122H. The C-phase leg has a low side switch element 123L and a high side switch element 123H. As a switch element, FET or IGBT can be used, for example. Hereinafter, an example using a MOSFET as a switch element will be described, and the switch element may be described as SW. For example, the low

side switch elements

121L, 122L and 123L are described as

SW

121L, 122L and 123L.

The first inverter 120 includes three

shunt resistors

121R, 122R and 123R included in a current sensor 150 (see FIG. 2) for detecting the current flowing in the winding of each phase A, B and C. . Current sensor 150 includes a current detection circuit (not shown) that detects the current flowing in each shunt resistor. For example, the

shunt resistors

121R, 122R and 123R are respectively connected between the three low side switch elements included in the three legs of the first inverter 120 and the GND. Specifically, shunt resistor 121R is electrically connected between SW121L and SW111, shunt resistor 122R is electrically connected between SW122L and SW111, and shunt resistor 123R is between SW123L and SW111. Electrically connected. The resistance value of the shunt resistor is, for example, about 0.5 mΩ to 1.0 mΩ.

Similar to the first inverter 120, the second inverter 130 includes a bridge circuit having three legs. The A-phase leg has a low side switch element 131L and a high side switch element 131H. The B-phase leg has a low side switch element 132L and a high side switch element 132H. The C-phase leg has a low side switch element 133L and a high side switch element 133H. In addition, the second inverter 130 includes three

shunt resistors

131R, 132R and 133R. The shunt resistors are connected between the three low side switch elements included in the three legs and GND.

The number of shunt resistors is not limited to three for each inverter. For example, it is possible to use two shunt resistors for A phase and B phase, two shunt resistors for B phase and C phase, and two shunt resistors for A phase and C phase. The number of shunt resistors to be used and the arrangement of the shunt resistors are appropriately determined in consideration of product cost, design specifications and the like.

As described above, the second inverter 130 has substantially the same structure as the structure of the first inverter 120. In FIG. 1, for convenience of the description, for example, the inverter on the left side of the drawing is represented as a first inverter 120, and the inverter on the right side is represented as a second inverter 130. However, such notations should not be construed with the intention of limiting the present disclosure. For example, the first and

second inverters

120 and 130 may be used as components of the inverter unit 100 without distinction.

[1-2. Structure of Power Conversion Device 1000 and Motor Module 2000 FIG. 2 schematically shows a block configuration of the motor module 2000 according to the present embodiment, and mainly shows a block configuration of the power conversion device 1000. As shown in FIG.

Power converter 1000 includes inverter unit 100 and motor controller 300. The motor module 2000 includes a power converter 1000 and a motor 200.

The motor module 2000 may be modularized and manufactured and sold as an electromechanical integrated motor having, for example, a motor, a sensor, a driver and a controller. In addition, the power conversion device 1000 which is a unit other than the motor 200 can be modularized, manufactured and sold.

The motor control device 300 includes, for example, a power supply circuit 310, an angle sensor 320, an input circuit 330, a controller 340, a drive circuit 350, and a ROM 360. The motor control device 300 is a control circuit that is connected to the inverter unit 100 and drives the motor 200 by controlling the inverter unit 100.

The motor control device 300 can realize closed loop control by controlling the target position, rotational speed, current, and the like of the rotor of the motor 200. Motor control device 300 may be replaced with angle sensor 320, and may be provided with a torque sensor. In this case, the motor control device 300 can control the target motor torque.

The power supply circuit 310 generates DC voltages (for example, 3 V, 5 V) necessary for each block in the circuit.

The angle sensor 320 is, for example, a resolver or a Hall IC. Alternatively, the angle sensor 320 is also realized by a combination of an MR sensor having a magnetoresistive (MR) element and a sensor magnet. The angle sensor 320 detects a rotation angle of the rotor (hereinafter referred to as “rotation signal”), and outputs a rotation signal to the controller 340.

Input circuit 330 receives a motor current value (hereinafter referred to as “actual current value”) detected by current sensor 150, and converts the level of the actual current value to the input level of controller 340 as necessary. , And outputs the actual current value to the controller 340. The input circuit 330 is, for example, an analog-to-digital converter.

The controller 340 is an integrated circuit that controls the drive circuit 350, and is, for example, a microcontroller or a field programmable gate array (FPGA).

The controller 340 controls the switching operation (turn on or off) of each SW in the first and

second inverters

120 and 130 of the inverter unit 100. The controller 340 sets a target current value according to the actual current value, the rotation signal of the rotor, etc. to generate a PWM signal, and outputs it to the drive circuit 350. The controller 340 may control on / off of each SW in the power shutoff circuit 110 of the inverter unit 100.

The drive circuit 350 is typically a gate driver (or pre-driver). The drive circuit 350 generates a control signal (gate control signal) for controlling the switching operation of the MOSFET of each SW in the first and

second inverters

120 and 130 in accordance with the PWM signal, and supplies the control signal to the gate of each SW. In addition, the drive circuit 350 may generate a control signal for controlling on / off of each SW in the power shutoff circuit 110 according to an instruction from the controller 340. When the drive target is a low voltage driveable motor, the gate driver may not be required. In that case, the function of the gate driver may be implemented in the controller 340.

The ROM 360 is electrically connected to the controller 340. The ROM 360 is, for example, a writable memory (for example, a PROM), a rewritable memory (for example, a flash memory), or a read only memory. The ROM 360 stores a control program including instructions for causing the controller 340 to control the power conversion apparatus 1000. For example, the control program is temporarily expanded in a RAM (not shown) at boot time.

[1-3. Operation of Power Converter 1000]

<Control when normal>

The motor control device 300 turns on all the

SWs

111, 112, 113 and 114 of the power shutoff circuit 110. Thereby, the power supply 101 and the first inverter 120 are electrically connected, and the power supply 101 and the second inverter 130 are electrically connected. In addition, the first inverter 120 and GND are electrically connected, and the second inverter 130 and GND are electrically connected. The

switches

115 and 116 for reverse connection protection of the power supply shutoff circuit 110 are always on. In this connected state, the motor control device 300 drives the motor 200 by energizing the windings M1, M2 and M3 using both of the first and

second inverters

120, 130. In the present specification, energization of a three-phase winding is referred to as "three-phase energization control".

For example, the motor control device 300 performs three-phase energization control by switching control of the SW of the first inverter 120 and the SW of the second inverter 130 in opposite phases (phase difference = 180 °). For example, focusing on the A-phase H bridge, when the SW 121 L turns on, the SW 131 L turns off, and when the SW 121 L turns off, the SW 131 L turns on. Similarly, when the SW 121 H is turned on, the SW 131 H is turned off, and when the SW 121 H is turned off, the SW 131 H is turned on. The B-phase and C-phase H bridges are also controlled in the same manner as the A-phase H bridge.

FIG. 3 exemplifies a current waveform (sine wave) obtained by plotting current values flowing in the A-phase, B-phase, and C-phase windings of the motor 200 when the power conversion device 1000 is controlled according to three-phase energization control. doing. The horizontal axis indicates the motor electrical angle (deg), and the vertical axis indicates the current value (A). In the current waveform of FIG. 3, current values are plotted every 30 ° of electrical angle. I _pk represents the maximum current value (peak current value) of each phase.

In the current waveform shown in FIG. 3, the sum of the currents flowing in the three-phase winding considering the direction of the current is "0" for each electrical angle. However, according to the circuit configuration of the inverter unit 100, the currents flowing through the three-phase windings can be controlled independently, so it is also possible to perform control such that the sum of the currents does not become "0". In that case, it should be noted that, strictly speaking, the sum of the currents flowing through the three-phase windings does not become “0” at each electrical angle, since the zero-phase current can flow in the circuit of the inverter. For example, the motor control device 300 can control the switching operation of each SW of the first and

second inverters

120 and 130 by PWM control that obtains the current waveform shown in FIG. 3.

<Control at the time of abnormality>

As described above, the abnormality mainly means that a failure occurs in the switch element (FET). The failure of the FET can be roughly divided into “open failure” and “short failure”. "Open fault" refers to a fault in which the source-drain of FET is opened (in other words, resistance rds between source-drain becomes high impedance), and "short fault" is in the source-drain of FET Refers to a short circuit failure. The open failure of the switch element SW refers to a failure in which the SW is always in the off (cutoff) state and is not in the on (conducting) state. The short failure of the switch element SW indicates a failure in which the SW is always in the on state and is not in the off state.

Refer back to FIG. If a failure occurs during the operation of the power conversion device 1000, it is usually considered that a random failure occurs in which one of the 16 FETs fails at random. However, it is assumed that a chained failure occurs in which a plurality of FETs fail in a chained manner. The chained failure means, for example, simultaneous occurrence of failure in the high side switch device and the low side switch device of one leg. The present disclosure covers these failures.

When the power converter 1000 is used for a long time, random failures may occur. The random failure is different from the manufacturing failure that may occur at the time of manufacturing. If even one of the plurality of SWs of the two inverters fails, normal three-phase conduction control is no longer possible.

As an example of failure detection, the drive circuit 350 monitors the voltage Vds between the drain and source of SW, and detects a failure of SW by comparing Vds with a predetermined threshold voltage. The threshold voltage is set in the drive circuit 350, for example, by data communication with an external IC (not shown) and an external component. The drive circuit 350 is connected to the port of the controller 340 and notifies the controller 340 of a failure detection signal. For example, when the drive circuit 350 detects a failure of the SW, the drive circuit 350 asserts a failure detection signal. When the controller 340 receives the asserted fault detection signal, the controller 340 reads the internal data of the drive circuit 350 to determine which one of the plurality of SWs is faulty.

As another example of failure detection, the controller 340 can also detect a failure of the SW based on the difference between the actual current value of the motor and the target current value. However, the failure detection is not limited to these methods, and a wide variety of known methods for failure detection can be used.

When the failure detection signal is asserted, the controller 340 switches control of the power conversion device 1000 from normal control to abnormal control. For example, the timing at which control is switched from normal to abnormal is about 10 msec to 30 msec after the fault detection signal is asserted.

Power converter 1000 has first and second drive modes as drive modes in control at the time of abnormality. The first drive mode is a mode in which three-phase conduction control is performed using the neutral point of the motor 200 configured to one of the first and

second inverters

120 and 130 and the other.

FIG. 4 is a diagram for explaining the on / off state of another SW when the SW 121 L of the A-phase leg of the first inverter 120 fails. It is assumed that SW 121 L has an open failure. In that case, the power conversion device 1000 (mainly the motor control device 300) turns on all the

high side SWs

121H, 122H and 123H, and turns off the

low side SW

122L, 123L other than the SW 121L. By this control, the node potential of the A phase leg between SW121H and SW121L, the node potential of the B phase leg between SW122H and SW122L, and the node potential of the C phase leg between SW123H and SW123L in the first inverter 120 are all It becomes equal potential. As a result, the node N1 on the high side of the first inverter 120 can function as a neutral point. In the present specification, that the nodes N1 and N2 on the high side or low side of the inverter function as neutral points is expressed as "a neutral point is configured". For example, when the high side SW 121 H fails, the low side node N 2 can function as a neutral point.

When the first drive mode is selected, the motor connection switches from the connection of the full H bridge to the Y connection. The motor control device 300 performs three-phase conduction control, that is, Y-connection driving, by performing PWM control on the switch elements of the second inverter 130 using the neutral point of the motor 200 configured in the first inverter 120.

The second drive mode is a mode in which the two-phase winding of the three phases is energized using both the first and

second inverters

120 and 130. Energizing the two-phase winding is referred to as "two-phase conduction control". For example, it is assumed that the SW 121 L has an open failure. In that case, when the second drive mode is selected, the motor control device 300 energizes the windings M2 and M3 using the B-phase and C-phase H bridges other than the A-phase H bridge including the failed SW 121L. Two-phase energization control is performed.

FIG. 5 shows a TN curve representing the relationship between the rotational speed (rps) per unit time of the motor and the normalized torque T (N · m). FIG. 5 shows respective TN curves in the three-phase conduction control, the Y-connection drive and the two-phase conduction control. The horizontal axis indicates the rotational speed (rps), and the vertical axis indicates the normalized torque T (N · m).

The respective regions of the Y-connection drive and the TN curve in the two-phase conduction control are included in the region of the TN curve in the normal drive, that is, in the normal three-phase conduction control. When the control at the normal time can not be performed, the motor control using the area of the TN curve of the Y connection drive or the two-phase current control can be performed. However, when only Y connection drive is selected in the control at the time of abnormality, the motor output characteristic in the high speed rotation region is limited, and when only the two-phase energization control is selected, the motor output characteristic in the high torque region Limits arise.

In the present embodiment, the motor control device 300 switches between the first drive mode and the second drive mode. More specifically, motor control apparatus 300 switches between the first drive mode and the second drive mode according to at least one of the torque command value and the speed information. Alternatively, the motor control device 300 switches between the first drive mode and the second drive mode in accordance with the output command value. The speed information is, for example, a rotation signal of a rotor that indicates a speed command value or an actual speed. Hereinafter, an embodiment using a speed command value as speed information will be described.

The motor control device 300 preferably selects the first drive mode in the high torque region of the TN curve, and selects the second drive mode in the high speed rotation region. The reason is that in the first drive mode, it is possible to flow the phase current equivalent to the normal three-phase energization control in the winding, and in the second drive mode the phase voltage equivalent to the normal three-phase energization control It is because it becomes possible to apply to a winding. In FIG. 5, motor drive may be performed using either the first or second drive mode in a region where the regions of the T-N curves of Y-connection drive and two-phase conduction control overlap each other.

FIG. 6 illustrates a control flow for switching between the first drive mode and the second drive mode in accordance with the speed command value.

In one aspect, the motor control device 300 switches between the first drive mode and the second drive mode according to the speed command value. For example, when an assert signal indicating failure is asserted, the motor control device 300 switches motor control from normal control to abnormal control (step S100). The motor control device 300 compares the speed command value with the speed threshold (step S200). The motor control device 300 selects the first drive mode when the speed command value is equal to or less than the speed threshold (step S300), and selects the second drive mode when the speed command value is larger than the speed threshold (step S400). ). The motor control device 300 repeatedly executes the determination of step S200 until the motor control ends (step S500).

FIG. 7 illustrates a control flow for switching between the first drive mode and the second drive mode according to the torque command value.

In one aspect, the motor control device 300 switches between the first drive mode and the second drive mode according to the torque command value. For example, when an assert signal indicating failure is asserted, the motor control device 300 switches motor control from normal control to abnormal control (step S100). The motor control device 300 compares the torque command value with the torque threshold (step S200). Motor control device 300 selects the second drive mode when the torque command value is equal to or less than the torque threshold (step S300), and selects the first drive mode when the torque command value is greater than the torque threshold (step S400). ). The motor control device 300 repeatedly executes the determination of step S200 until the motor control ends (step S500).

According to the present embodiment, in the control at the time of abnormality, the high motor output equivalent to the three-phase energization control at the normal time by switching the first and second drive modes mutually according to the speed command value or the torque command value. It becomes possible to obtain characteristics.

In the present specification, the control at the time of abnormality has been described by taking the case where a failure occurs in the switch element of the first inverter 120 as an example. However, it goes without saying that control at the time of abnormality when a failure occurs in the switch element of the second inverter 130 can also be performed in the same manner as that of the first inverter 120.

Second Embodiment

FIG. 8 schematically shows a typical configuration of the electric power steering apparatus 3000 according to the present embodiment.

Vehicles such as automobiles generally have an electric power steering device. The electric power steering apparatus 3000 according to the present embodiment has a steering system 520 and an auxiliary torque mechanism 540 that generates an auxiliary torque. Electric power steering apparatus 3000 generates an assist torque that assists the steering torque of the steering system generated by the driver operating the steering wheel. The assist torque reduces the burden on the driver's operation.

The steering system 520 includes, for example, a steering handle 521, a steering shaft 522,

free shaft joints

523A and 523B, a rotating shaft 524, a rack and pinion mechanism 525, rack shafts 526, left and right ball joints 552A and 552B,

tie rods

527A and 527B,

knuckles

528A, 528B, and left and

right steering wheels

529A, 529B.

The auxiliary torque mechanism 540 includes, for example, a steering torque sensor 541, an electronic control unit (ECU) 542 for a car, a motor 543, and a reduction mechanism 544. The steering torque sensor 541 detects a steering torque in the steering system 520. The ECU 542 generates a drive signal based on a detection signal of the steering torque sensor 541. The motor 543 generates an auxiliary torque corresponding to the steering torque based on the drive signal. The motor 543 transmits the generated assist torque to the steering system 520 via the reduction mechanism 544.

The ECU 542 includes, for example, the controller 340 and the drive circuit 350 according to the first embodiment. In automobiles, an electronic control system is built around an ECU. In the electric power steering apparatus 3000, for example, a motor drive unit is constructed by the ECU 542, the motor 543 and the inverter 545. The motor module 2000 according to the first embodiment can be suitably used for the unit.

Electric power steering apparatus 3000 can be mounted, for example, on a vehicle having a parking mode and a traveling mode. The parking mode is a mode for traveling at a speed of approximately 20 km / h or less, and the traveling mode is a mode for traveling at a speed of approximately 20 km / h or more. It is possible to associate the first and second drive modes of the power conversion device 1000 with the parking mode and the traveling mode of the vehicle, respectively. The vehicle may be equipped with a motor control system such as shift by wire, steering by wire, x by wire such as brake by wire, or a traction motor. For example, the electric power steering apparatus 3000 mounted with the motor module 2000 is mounted on an autonomous vehicle corresponding to levels 0 to 5 (standards of automation) defined by the Japanese government or the Road Traffic Safety Administration (NHTSA) of the US Department of Transportation. obtain.

It is assumed that a switch failure occurs in the inverter unit 100 of the motor module 2000. In this case, when the parking mode is selected as the control mode of the vehicle, motor control device 300 selects the first drive mode as the drive mode of power conversion device 1000. On the other hand, when the travel mode is selected as the control mode of the vehicle, motor control device 300 selects the second drive mode as the drive mode of power conversion device 1000.

For example, high torque is required for low speed steering such as when parking a vehicle or when making a right turn or left turn at an intersection. In that case, high torque can be obtained by selecting the first drive mode as the drive mode of power conversion device 1000. On the other hand, for example, when the vehicle travels in the travel mode, high torque is not particularly required, and low torque is sufficient. Rather, rapid steering may be required, for example when avoiding obstacles while driving. In that case, by selecting the second drive mode as the drive mode of power conversion device 1000, motor 200 can be rotated at high speed.

The driver may manually switch the parking mode and the travel mode, or the vehicle may automatically switch those modes based on, for example, speed information. Specifically,

(1) For example, the control unit of the vehicle determines switching between the two modes based on the vehicle speed, and notifies the controller 340 of the motor module 2000 of the determination result;

(2) For example, the control unit of the vehicle determines switching between the two modes according to the signal of the shift lever, and notifies the controller 340 of the motor module 2000 of the determination result. For example, when the shift lever is switched to reverse (R), the control unit instructs the controller 340 to select the first drive mode; (3) For example, a vehicle capable of performing automatic driving has a roadway It has a traveling mode for automatically traveling and a parking mode for automatically parking a vehicle in a parking space. When the driver selects the travel mode, the control unit of the vehicle receives the selection and instructs the controller 340 to select the second drive mode, and when the driver selects the parking mode, the control unit controls the first The controller 340 is instructed to select a drive mode.

According to the present embodiment, for example, by associating the first and second drive modes with the parking mode and the traveling mode of the vehicle, respectively, and switching between those modes in the control at the time of abnormality, It is possible to obtain high motor output characteristics equivalent to phase energization control. As a result, it is possible to provide an electric power steering apparatus having an optimum motor output characteristic according to the control mode of the vehicle.

Embodiments of the present disclosure can be widely used in a variety of devices equipped with various motors, such as vacuum cleaners, dryers, ceiling fans, washing machines, refrigerators, and electric power steering devices.

100: inverter unit, 101: power supply, 102: coil, 103: capacitor, 110: power switching circuit, 111: first switch element, 112: second switch element, 113: third switch element, 114: fourth switch element , 115: fifth switch element, 116: sixth switch element, 120: first inverter, 130: second inverter, 200: motor, 1000: power converter, M1, M2, M3: winding

Claims

A power converter that converts power from a power supply into power supplied to a motor having n-phase (n is an integer of 3 or more) windings,

A first inverter connected to one end of a winding of each phase of the motor;

A second inverter connected to the other end of the winding of each phase;

Equipped with

A first drive mode for performing n-phase conduction control using the neutral point of the motor configured to one and the other of the first and second inverters, and n− using both the first and second inverters A power conversion device, comprising: a second drive mode for performing one-phase energization control; and switching between the first drive mode and the second drive mode in an abnormal control.
The power converter according to claim 1, wherein the first and second drive modes are switched between each other according to at least one of a torque command value and speed information.
The power conversion device according to claim 2, wherein the first drive mode is selected in a high torque area of a TN curve of the motor, and the second drive mode is selected in a high speed rotation area.
The first and second drive modes are mutually switched according to the speed information,

The first driving mode is selected when the value of the speed information is equal to or less than a speed threshold, and the second driving mode is selected when the value of the speed information is larger than the speed threshold. Power converter as described.
The first and second drive modes are mutually switched according to the torque command value,

The second drive mode is selected when the torque command value is equal to or less than a torque threshold, and the first drive mode is selected when the torque command value is greater than the torque threshold. Power converter.
The first or second drive mode is selected in a region where the drive region of the first drive mode and the drive region of the second drive mode overlap with each other in the TN curve of the motor. Power converter according to claim 1.
A first switch element for switching connection / disconnection between the first inverter and the ground;

A second switch element for switching connection / disconnection between the first inverter and the power supply;

A third switch element for switching connection / disconnection between the second inverter and the ground;

A fourth switch element for switching connection / disconnection between the second inverter and the power supply;

The power converter according to any one of claims 1 to 6, further comprising
The motor control device further controls a switching operation of switch elements of the first and second inverters, and switches between the first drive mode and the second drive mode in the control at the time of the abnormality. The power converter according to any one of to 7.
Motor,

A power converter according to any one of claims 1 to 8,

Motor module comprising:
An electric power steering apparatus comprising the motor module according to claim 9.
11. The electric power steering apparatus according to claim 10, mounted on a vehicle having a parking mode and a traveling mode,

In the control at the time of the abnormality of the power converter, when the control mode of the vehicle is the parking mode, the first drive mode is selected as a drive mode of the power converter, and the control mode of the vehicle is the traveling When in the mode, the second drive mode is selected as the drive mode.