Semiconductor device, switching method, and program

Abstract

The invention relates to a semiconductor device, a switching method, and a program. Provided are a semiconductor device, a switching method, and a program that can prevent an overcurrent from flowing through a winding inside the motor. The semiconductor device 100a determines whether the current value of the winding exceeds the threshold value after a predetermined time on the basis of at least one of the inductance value and the resistance value of the winding inside the motor 10, and determines whether the current value of the winding exceeds the threshold value on the basis of a result of the determination by the determination unit 363. A switching unit 364 is included for switching the control mode of the motor 10.

Description

[0001] Cross - Reference to Related Applications

[0002] The disclosure of Japanese Patent Application No. 2023-202206, filed on November 29, 2023, including the specification, drawings, and abstract, is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a semiconductor device, a switching method, and a program for switching a control mode of an electric motor. Background Art

[0004] In order to achieve miniaturization and high efficiency of an automotive electric motor, it is necessary to rotate the electric motor at high speed.

[0005] The disclosed technologies are listed below.

[0006] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2011-188609

[0007] Patent Document 1 discloses a square wave control mode when the electric motor rotates at high speed. Summary of the Invention

[0008] When the electric motor rotates at high speed, there is a problem that an overcurrent may flow into the windings inside the electric motor.

[0009] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0010] According to an embodiment of the semiconductor device, based on at least one of the inductance value and the resistance value of the windings inside the electric motor, a determination unit is configured to determine whether the current value of the windings exceeds a threshold after a predetermined time, and based on the determination result of the determination unit, the determination unit includes a switching unit for switching the control mode of the electric motor.

[0011] According to an embodiment of the switching method, based on at least one of the inductance value and the resistance value of the windings inside the electric motor, based on the determination result of a determination step, the determination step determines whether the current value of the windings exceeds a threshold after a predetermined time, and a switching step switches the control mode of the electric motor.

[0012] According to an embodiment of the program, based on at least one of the inductance value and the resistance value of the windings inside the electric motor, a determination process is configured to determine whether the current value of the windings exceeds a threshold after a predetermined time, and based on the determination result of the determination process, a control mode of the electric motor It is configured to execute a switching process for switching.

[0013] According to one embodiment, it is possible to provide a semiconductor device, a switching method, and a program that can prevent an overcurrent from flowing in the windings inside the electric motor. Brief Description of the Drawings

[0014] Figure 1 is a block diagram showing the configuration of a semiconductor device according to a comparative example.

[0015] Figure 2 is a perspective view showing the configuration of an IPS (Inductive Position Sensor).

[0016] Figure 3 is a graph showing the time variation of the current value of the windings of each phase of an electric motor.

[0017] Figure 4 is a block diagram showing the configuration of a semiconductor device according to the first embodiment.

[0018] Figure 5 is a block diagram showing the functional configuration of an MCU (Microcontroller Unit) according to the first embodiment.

[0019] Figure 6 is a graph showing the time variation of the current value of an electric motor winding.

[0020] Figure 7 is a graph showing the time variation of the current value of an electric motor winding.

[0021] Figure 8 is a diagram for explaining the timing of switching voltage.

[0022] Figure 9 is a diagram for explaining the delay in the timing of switching voltage.

[0023] Figure 10 is a diagram for explaining the time variation of an ideal current value.

[0024] Figure 11 is a diagram for explaining the time variation of an actual current value.

[0025] Figure 12 is a flowchart showing an example of the operation of a semiconductor device according to the first embodiment.

[0026] Figure 13 is a diagram for explaining the operation of a semiconductor device according to the first embodiment. Detailed Description

[0027] For clarity of explanation, the following description and drawings are appropriately omitted and simplified. Additionally, the corresponding components described as functional blocks for performing various processes in the drawings can be configured according to hardware, a CPU, a memory, or other circuitry, and according to software, can be implemented in a program loaded into the memory, etc. Thus, those skilled in the art will understand that these functional blocks can be implemented in various forms by hardware, software running on the hardware, or a combination thereof, and are not limited to any one form. In the drawings, the same elements are denoted by the same reference numerals, and their repeated description is omitted as needed.

[0028] The above program also includes a set of instructions (or software code) for causing a computer to perform one or more functions described in the embodiments when read into the computer. The program can be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, a computer-readable medium or a tangible storage medium includes: random access memory (RAM), read-only memory (ROM), flash memory, solid state drive (SSD), or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray disc, or other optical disc storage devices, magnetic tape cartridges, tapes, magnetic disk storage devices, or other magnetic storage devices. The program can be transmitted on a transient computer-readable medium or a communication medium. By way of example and not limitation, a temporary computer-readable medium or a communication medium includes propagated signals in electrical, optical, acoustic, or other forms.

[0029] (Considerations Leading to the Embodiments)

[0030] Figure 1 FIG. 10 is a block diagram showing the configuration of a semiconductor device 100 according to a comparative example. The semiconductor device 100 controls the rotation of a motor 10. The semiconductor device 100 includes an IPS (inductive position sensor) 20 and an inverter 30.

[0031] Inside the motor 10, windings for generating a magnetic field are provided. For example, the motor 10 is a three-phase motor including a U-phase winding, a V-phase winding, and a W-phase winding. The motor 10 can be a two-phase motor, a four-phase or more-phase motor. A target metal 11 detected by the IPS 20 is mounted on the shaft of the motor 10 or the like.

[0032] The IPS 20 supplies an analog signal indicating the rotation angle of the motor 10 to the inverter 30. The IPS 20 includes a coil pattern 21 and a sensor circuit 22. The coil pattern 21 includes a transmitting coil and a receiving coil. The sensor circuit 22 outputs a transmission signal to the transmitting coil and obtains a reception signal of the receiving coil. Although a resolver can be used instead of the IPS 20, the semiconductor device 100 can be miniaturized by using the IPS 20.

[0033] Figure 2is a perspective view showing an exemplary configuration of the IPS20. The feather-shaped component W is attached to the shaft 12 of the motor 10, and the target metal 11 is provided in the component W. The sensor circuit 22 detects the current flowing through the coil pattern 21 and outputs an analog signal representing the rotational angle of the motor 10.

[0034] Referring to Figure 1 , the inverter 30 includes an isolator 31, a PMIC (Power Management Integrated Circuit) 32, an LDO (Low Dropout) 33, an IGBT (Insulated Gate Bipolar Transistor) 34, a gate driver IC 35, and an MCU (Microcontroller Unit) 36.

[0035] The isolator 31 outputs the signal input via the external interface to the MCU 36. For example, the isolator 31 is an optocoupler.

[0036] The PMIC 32 generates an internal voltage from the voltage of the battery and supplies the generated internal voltage to the MCU 36.

[0037] The LDO 33 generates a constant voltage lower than the battery voltage and supplies the generated voltage to the IPS20.

[0038] The IGBT 34 generates a voltage across the windings of the motor 10. For example, the IGBT 34 consists of the upper and lower arms of the U phase, the upper and lower arms of the V phase, and the upper and lower arms of the W phase. Any switching element other than the IGBT (e.g., MOS transistor) can be used.

[0039] The gate driver IC 35 drives the gate of the corresponding IGBT 34.

[0040] The MCU 36 is equipped with an ADC (Analog-to-Digital Converter) 41, which performs AD conversion on the analog signal from the IPS20 at regular time intervals. Thus, the MCU 36 obtains a digital signal indicating the rotational angle of the motor 10. When the control mode of the motor 10 is the square wave control mode, the MCU 36 outputs a pulse to the gate driver IC 35 based on the rotational angle of the motor 10. The MCU 36 can also control the motor 10 in the PWM control mode using known techniques.

[0041] Figure 3 represents the ideal time variation of the current values of the three phases of the motor 10 controlled by the square wave control mode. The horizontal axis represents time, and the vertical axis represents the current value. The solid line, the dashed line, and the dotted line represent the U-phase current, the V-phase current, and the W-phase current, respectively. When the current flows in a predetermined direction, the current value is expressed by a positive value, and when the current flows in the opposite direction, the current value is expressed by a negative value. Ideally, the amount of fluctuation of the current value in the positive direction is equal to the amount of fluctuation of the current value in the negative direction.

[0042] Next, the present inventor will describe the problems studied. When the motor 10 is controlled in the square wave control mode, due to delays in the process, etc., the timing of the MCU 36 switching the pulse output may deviate from the ideal timing. In this case, Figure 3 the change amount in the positive direction and the change amount in the negative direction in

[0043] (First Embodiment)

[0044] Figure 4 is a block diagram illustrating the configuration of the semiconductor device 100a according to the first embodiment. By using comparison Figure 1 and 4 , a current sensor 13 is added to the motor 10, and the MCU 36a is used instead of the MCU 36.

[0045] The current sensor 13 measures the current value of the winding of the motor 10. The current sensor 13 outputs an analog voltage signal corresponding to the current value to the MCU 36a.

[0046] The MCU 36a includes an ADC 41, an ADC 42, a pulse output unit 43, a timer 44, and a CPU (Central Processing Unit) 45.

[0047] As described above, the ADC 41 performs AD conversion on the analog signal received from the IPS20 at regular time intervals to generate a digital signal indicating the rotation angle of the motor 10. The constant time interval can be measured by the timer 44.

[0048] The ADC 42 generates a digital signal indicating the current reading of the winding of the motor 10 by performing AD conversion on the analog signal received from the current sensor 13.

[0049] The pulse output unit 43 outputs a pulse to the gate driver IC 35 according to the instruction of the CPU 45.

[0050] The timer 44 notifies the CPU 45 at regular intervals. The timer 44 interrupts the CPU 45 at regular intervals. The constant time can be determined according to the rotation speed of the motor 10. The rotation speed can be calculated based on the measured IPS20.

[0051] The CPU 45 reads and executes a program from a memory (not shown), and the MCU 36a implements multiple functions. Figure 5It is a block diagram showing the functional configuration of the MCU 36a. The MCU 36a includes a control unit 361, a calculation unit 362, a determination unit 363, and a switching unit 364.

[0052] The control unit 361 of the MCU 36a outputs pulses to the pulse output unit 43 according to the control mode of the motor 10. The control mode of the motor 10 is set to a square wave control mode or a PWM control mode. If the control mode is a rectangular wave control mode, the control unit 361 checks the rotation angle of the motor 10 at the timing generated by the timer 44 and controls the pulse output corresponding to the rotation angle.

[0053] Refer to Figures 6 to 11 , and a description of the rectangular wave control mode will be given. Figure 6 The upper figure in shows the time variation of the voltage value (voltage value) applied to the winding, and the lower figure shows the time variation of the winding current value. Figure 6 The horizontal direction (horizontal axis) in represents time. The amount of change in the current value per unit time is determined by the resistance value and inductance value of the winding. Further, as Figure 7 shown, the maximum value of the current value is determined according to the length of the period during which the voltage value is at the H level. Figure 7 The horizontal direction (horizontal axis) in represents time.

[0054] Figure 8 The upper figure in shows the time variation of the rotation angle of the motor 10, and the lower figure shows an example of the ideal time variation of the voltage value. Figure 8 The horizontal direction (horizontal axis) in represents time. The short straight lines extending vertically in the lower figure represent the timing of the rise and fall of the voltage value, that is, the switching timing of the voltage pattern. Ideally, the voltage value is switched at this switching timing.

[0055] Figure 9 The upper figure in represents the ideal time variation of the winding voltage value. Figure 9 The horizontal direction in represents time. In fact, due to delays in processing, etc., as shown in the following figure, there are cases where there is a timing delay in switching the winding voltage value. The horizontal arrow represents the delay amount between the timing of switching the voltage value and the ideal timing.

[0056] Figure 10 shows the time variation of the current value when the timing of switching the voltage value of the winding is ideal. Figure 10 The horizontal direction (horizontal axis) in represents time. Figure 10The upper figure above shows the time variation of the voltage value, and the lower figure shows the time variation of the current value. The dashed line indicates the overcurrent threshold. The current value increases during the high voltage period (also referred to as the first period) and decreases during the low voltage period (also referred to as the second period). For example, if the rotational speed of the motor 10 is constant and there is no such delay as mentioned above, the lengths of the first period and the second period are equal to each other.

[0057] Figure 11 Shows the time variation of the current value when the timing at which the voltage value of the winding is switched is not ideal. Figure 11 The horizontal direction (horizontal axis) in shows time. For example, if the rotational speed of the motor 10 is constant and there is the above-mentioned delay, the lengths of the first period and the second period are different from each other. When the timing at which the first period ends is delayed, the current value at the end t2 of the second period does not return to the current value at the start t1 of the first period. This may cause the current value to exceed the threshold. If the current exceeds the overcurrent threshold, the power supply of the semiconductor device 100a is cut off to protect the winding.

[0058] Refer to Figure 5 Calculation unit 362 determines the resistance value of the winding based on the temperature information of the winding of the motor 10. Calculation unit 362 determines the inductance value of the winding based on the current value of the winding of the motor 10. Calculation unit 362 calculates the increase amount of the current value per unit time based on the resistance value and the inductance value. Incidentally, the change amount of the current value per unit time can be determined in advance based on the resistance value and the inductance value. In this case, the MCU 36a may not include the calculation unit 362.

[0059] Determination unit 363 determines whether the current value of the winding exceeds the threshold after a constant time based on at least one of the inductance value and the resistance value of the winding. Timer 44 can measure a specific time. Specifically, determination unit 363 determines whether the current value of the winding exceeds the threshold after a certain time based on the increase of the winding current value per unit time. For example, determination unit 363 can multiply the increase amount of the current value per unit time by the constant time and add the multiplication result to the current value based on the measurement result of the current sensor 13.

[0060] Switching unit 364 switches the control mode of the motor 10 based on the determination result of determination unit 363. Specifically, when it is determined that the current value exceeds the threshold, switching unit 364 switches the control mode from the rectangular wave control mode to the PWM control mode. Further, when it is determined that the current value does not exceed the threshold, switching unit 364 switches the control mode from the PWM control mode to the rectangular wave control mode.

[0061] Refer to Figure 12, an exemplary operation of the semiconductor device 100a will be described. First, steps A to B are executed, and steps C to E are executed at each timing determined by the timer 44.

[0062] In step A, the MCU 36a of the semiconductor device 100a acquires a preset overcurrent threshold. The threshold can be previously stored in a storage device such as a memory. The threshold corresponds to Figure 13 "A" in Figure 13 The horizontal direction (horizontal axis) in represents time.

[0063] Referring to Figure 12 , in step B, the calculation unit 362 of the MCU 36a calculates the increase amount of the current value per unit time based on the resistance value determined by the temperature of the winding and the inductance value determined by the current value of the winding. Figure 13 The curve shown as "B" in can be approximated as a straight line with a constant slope. This slope corresponds to the increase amount of the current value per unit time.

[0064] Referring to Figure 12 , steps C to E can be executed only when the rotational speed of the motor 10 exceeds a predetermined speed. If the rotational speed of the motor 10 is less than the predetermined speed, the control mode of the motor 10 can be set to the PWM control mode.

[0065] In step C, the determination unit 363 of the MCU 36a determines whether the corresponding timing is included in the first time period. Figure 13 "C" in represents the first time period. Steps D to E can be executed only when each timing is included in the first time period.

[0066] Referring to Figure 12 , in step D, the determination unit 363 of the MCU 36a acquires the current value based on the measurement of the current sensor 13. Referring to Figure 13 , the current value corresponding to the point indicated by "D" is acquired.

[0067] Referring to Figure 12 , in step E, the determination unit 363 determines whether the current value before the next timing exceeds the threshold based on the increase amount calculated in step B and the current value obtained in step D, and the switching unit 364 switches the control mode of the motor 10 based on the determination result. For the switching unit 364, the control mode is the rectangular wave control mode, and if the current value of the following timing exceeds the threshold, the control mode can be switched to the PWM control mode. Further, for the switching unit 364, the control mode is the PWM control mode, and if the current value of the following timing does not exceed the threshold, the control mode can be switched to the rectangular wave control mode.

[0068] In the first embodiment, when the motor 10 rotates at high speed, overcurrent flowing in the winding is prevented, and the rotation of the motor 10 can be continued. Further, the semiconductor device 100a can achieve miniaturization and high efficiency of the motor 10.

[0069] Although the present invention made by the present inventors has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and needless to say, various modifications can be made without departing from the gist thereof.

Claims

1. A semiconductor device, comprising: a determination unit configured to determine whether the current value of the winding exceeds a threshold value after a predetermined time based on at least one of an inductance value and a resistance value of the winding inside the motor; as well as A switch unit is used to switch the control mode of the motor based on the determination result of the determination unit.

2. The semiconductor device according to claim 1, When the current value is determined to exceed the threshold value, the switch unit switches the control mode from the rectangular wave control mode to the pulse width modulation (PWM) control mode.

3. The semiconductor device according to claim 1, When the current value is determined not to exceed the threshold value, the switch unit switches the control mode from the PWM control mode to the square wave control mode.

4. The semiconductor device according to claim 2, further comprising: a plurality of switching elements for generating a voltage to be applied to the winding; A gate driver, configured to drive the gate of each switching element; An inductive position sensor IPS, used to measure the rotation angle of the motor; as well as A control unit is configured to control the operation of the gate driver based on the control mode and the rotation angle.

5. The semiconductor device according to claim 4, The determination unit determines whether the timing generated by the timer is within a first period during which the current value increases, and when the timing is within the first period, the current value exceeds the threshold value.

6. The semiconductor device according to claim 1, further comprising a calculation unit configured to calculate an increase per unit time of the current value based on the inductance value and the resistance value, comprising: The determination unit determines whether the current value exceeds the threshold value based on the measurement result of the current sensor for measuring the current value and the increase amount per unit time.

7. The semiconductor device according to claim 2, When the rotation speed of the motor exceeds a predetermined speed, the determination unit determines whether the current value exceeds the threshold value.

8. A switching method, comprising: a determining step of determining whether the current value of the winding exceeds a threshold value after a predetermined time based on at least one of an inductance value and a resistance value of the winding inside the motor; as well as a switching step of switching the control mode of the motor based on the determination result of the determination step.

9. A program for causing a computer to run, comprising: a determination process for determining whether the current value of the winding exceeds a threshold value after a predetermined time based on at least one of an inductance value and a resistance value of the winding inside the motor; as well as A switching process is used to switch the control mode of the motor based on the determination result of the determination process.

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