Semiconductor device, switching method, and program

Abstract

To provide a semiconductor device, a switching method, and a program which can prevent an excess current from flowing to a winding inside a motor.SOLUTION: A semiconductor device 100a comprises: a determination unit 363 which determines whether or not a current value of a winding exceeds a threshold after a fixed time on the basis of at least either of an inductance value and a resistance value of the winding inside a motor 10; and a switching unit 364 which switches control modes of the motor 10 on the basis of a determination result of the determination unit 363.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a semiconductor device, a switching method, and a program for switching a control mode of a motor.

Background Art

[0002] In order to achieve miniaturization and high efficiency of an in-vehicle motor, it is necessary to rotate the motor at a high speed. Patent Document 1 describes using a rectangular wave control mode when rotating the motor at a high speed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the motor is rotated at a high speed, there is a problem that an overcurrent may flow through the windings inside the motor.

[0005] Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0006] A semiconductor device according to an embodiment includes a determination unit that determines whether a current value of the winding exceeds a threshold value after a certain time based on at least one of an inductance value and a resistance value of the winding inside the motor, and a switching unit that switches a control mode of the motor based on a determination result of the determination unit.

[0007] The switching method according to an embodiment includes a determination step of determining whether or not the current value of the winding exceeds a threshold value after a certain period of time based on at least one of the inductance value and the resistance value of the winding inside the motor, and a switching step of switching the control mode of the motor based on the determination result of the determination step.

[0008] A program according to an embodiment causes a computer to execute a determination process of determining whether or not the current value of the winding exceeds a threshold value after a certain period of time based on at least one of the inductance value and the resistance value of the winding inside the motor, and a switching process of switching the control mode of the motor based on the determination result of the determination process.

Advantages of the Invention

[0009] According to the above embodiment, it is possible to provide a semiconductor device, a switching method, and a program that can prevent an overcurrent from flowing through the winding inside the motor.

Brief Description of the Drawings

[0010]

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Mode for Carrying Out the Invention

[0011] For the sake of clarity of explanation, the following description and drawings are appropriately omitted and simplified. Also, each element described in the drawings as a functional block for performing various processes can be configured hardware-wise by a CPU, memory, and other circuits, and software-wise by a program loaded into the memory or the like. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by hardware, software operating on the hardware, or a combination thereof, and are not limited to any one of them. In each drawing, the same reference numerals are assigned to the same elements, and redundant explanations are omitted as necessary.

[0012] In addition, when the above-described program is loaded into a computer, it includes a set of instructions (or software code) for causing the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, the computer-readable medium or 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 (registered trademark) disc, or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may also be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, the transitory computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0013] Consideration Leading to Embodiments FIG. 1 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.

[0014] A winding for generating a magnetic field is provided inside the motor 10. The motor 10 is, for example, a three-phase motor and includes a U-phase winding, a V-phase winding, and a W-phase winding. Note that the motor 10 may be a two-phase motor or a motor with four or more phases. A target metal 11 detected by the IPS 20 is attached to the shaft or the like of the motor 10.

[0015] The IPS20 outputs an analog signal indicating the rotation angle of the motor 10 to the inverter 30. The IPS20 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 acquires the received signal of the receiving coil. A resolver may be used instead of the IPS20, but using the IPS20 can miniaturize the semiconductor device 100.

[0016] FIG. 2 is a perspective view showing an example of the 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 on the component W. The sensor circuit 22 detects the current flowing through the coil pattern 21 and outputs an analog signal indicating the rotation angle of the motor 10.

[0017] Referring to FIG. 1, the inverter 30 includes an insulating element 31, a PMIC (Power Management Integrated Circuit) 32, an LDO (Low Drop Out) 33, an IGBT (Insulated Gate Bipolar Transistor) 34, a gate driver 35, and an MCU (Micro Controller Unit) 36.

[0018] The insulating element 31 outputs the signal input via the external interface to the MCU 36. The insulating element 31 is, for example, a photocoupler.

[0019] The PMIC 32 generates an internal voltage from the battery voltage and supplies the generated internal voltage to the MCU 36.

[0020] The LDO 33 generates a constant voltage lower than the battery voltage and supplies the generated voltage to the IPS20.

[0021] The IGBT 34 generates the voltage applied to the windings of the motor 10. The IGBT 34 includes, for example, 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. Note that a switching element other than the IGBT (e.g., MOS transistor) may be used.

[0022] The gate driver 35 drives the gates of the respective IGBTs 34.

[0023] The MCU 36 includes an ADC (Analog Digital Converter) 41 and performs AD conversion on the analog signals from the IPS 20 at regular time intervals. Thereby, the MCU 36 acquires a digital signal indicating the rotation angle of the motor 10. When the control mode of the motor 10 is the rectangular wave control mode, the MCU 36 outputs a pulse to the gate driver 35 based on the rotation angle of the motor 10. Also, the MCU 36 can control the motor 10 in the PWM control mode using a known technique.

[0024] FIG. 3 shows the ideal time variation of the current values of the three phases of the motor 10 controlled in the rectangular wave control mode. The horizontal axis represents time, and the vertical axis represents the current value. The solid line, dotted line, and dashed-dotted line represent the U-phase current, V-phase current, and W-phase current, respectively. When the current flows in a predetermined direction, the current value is represented by a positive value, and when the current flows in the opposite direction, the current value is represented by a negative value. In an ideal case, the amount of variation of the current value in the positive direction is equal to the amount of variation of the current value in the negative direction.

[0025] Next, the problems studied by the inventor will be described. When the motor 10 is controlled in the rectangular wave control mode, the timing at which the MCU 36 switches the output of the pulse may deviate from the ideal timing due to processing delays or the like. In this case, the amount of variation in the positive direction and the amount of variation in the negative direction in FIG. 3 do not match each other, and there is a risk that the current value in the positive direction or the negative direction exceeds the overcurrent threshold. When an overcurrent occurs, the power supply of the semiconductor device 100 is cut off to protect the winding. Therefore, the semiconductor device 100 has a problem that it is difficult to continue the rotation of the motor 10.

[0026] Embodiment 1 FIG. 4 is a block diagram showing the configuration of the semiconductor device 100a according to Embodiment 1. Comparing FIG. 1 and FIG. 4, a current sensor 13 is added to the motor 10, and the MCU 36 is replaced with the MCU 36a.

[0027] 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.

[0028] 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.

[0029] As described above, the ADC 41 performs AD conversion on the analog signal received from the IPS 20 at regular time intervals, and generates a digital signal indicating the rotation angle of the motor 10. The regular time intervals may be measured by the timer 44.

[0030] The ADC 42 generates a digital signal indicating the current value of the winding of the motor 10 by performing AD conversion on the analog signal received from the current sensor 13.

[0031] The pulse output unit 43 outputs a pulse to the gate driver 35 according to an instruction from the CPU 45.

[0032] The timer 44 notifies the CPU 45 at regular intervals. The timer 44 may interrupt the CPU 45 at regular intervals. The regular time intervals may be determined according to the rotation speed of the motor 10. The rotation speed may be calculated based on the measurement result of the IPS 20.

[0033] When the CPU 45 reads and executes a program from a memory (not shown), the MCU 36a realizes a plurality of functions. FIG. 5 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.

[0034] The control unit 361 of the MCU 36a causes the pulse output unit 43 to output a pulse according to the control mode of the motor 10. The control mode of the motor 10 is set to a rectangular wave control mode or a PWM control mode. When the control mode is the 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 output of the pulse according to the rotation angle.

[0035] Referring to FIGS. 6 to 11, the rectangular wave control mode will be described. The upper diagram in FIG. 6 shows the time change of the value of the voltage (voltage value) applied to the winding, and the lower diagram shows the time change of the current value of the winding. The horizontal direction (horizontal axis) in FIG. 6 represents time. The amount of change of the current value per unit time is determined by the resistance value and inductance value of the winding. Also, as shown in FIG. 7, 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. The horizontal direction (horizontal axis) in FIG. 7 represents time.

[0036] The upper diagram in FIG. 8 shows the time change of the rotation angle of the motor 10, and the lower diagram shows an example of the ideal time change of the voltage value. The horizontal direction (horizontal axis) in FIG. 8 represents time. The short straight lines extending in the vertical direction in the lower diagram represent the rising and falling timings of the voltage value, that is, the switching timings of the voltage pattern. Ideally, the voltage value is switched at this switching timing.

[0037] The upper diagram in FIG. 9 represents the ideal time change of the voltage value of the winding. The horizontal direction in FIG. 9 represents time. In reality, due to processing delays or the like, as shown in the lower diagram, the timing at which the voltage value of the winding is switched may be delayed. The horizontal arrow represents the amount of delay in the timing of switching the voltage value from the ideal timing.

[0038] FIG. 10 shows the time variation of the current value when the timing at which the voltage value of the winding is switched is ideal. The horizontal direction (horizontal axis) in FIG. 10 represents time. The upper diagram in FIG. 10 shows the time variation of the voltage value, and the lower diagram shows the time variation of the current value. The dotted line represents the threshold value of the overcurrent. The current value increases during the period when the voltage value is high (also referred to as the first period) and decreases during the period when the voltage value is low (also referred to as the second period). For example, when the rotational speed of the motor 10 is constant and there is no delay as described above, the length of the first period and the length of the second period are equal to each other.

[0039] FIG. 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. The horizontal direction (horizontal axis) in FIG. 11 represents time. For example, when the rotational speed of the motor 10 is constant and there is the above-described delay, the length of the first period and the length of 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. As a result, there is a possibility that the current value exceeds the threshold value. When the current value exceeds the overcurrent threshold value, the power supply of the semiconductor device 100a is cut off to protect the winding.

[0040] Referring to FIG. 5, the calculation unit 362 determines the resistance value of the winding based on the temperature information of the winding of the motor 10. Further, the calculation unit 362 determines the inductance value of the winding based on the current value of the winding of the motor 10. The calculation unit 362 calculates the increase amount of the current value per unit time based on the resistance value and the inductance value. Note that the change amount of the current value per unit time may be determined in advance based on either the resistance value or the inductance value. In this case, the MCU 36a may not include the calculation unit 362.

[0041] The determination unit 363 determines whether the current value of the winding exceeds a threshold value after a certain period of time based on at least either the inductance value or the resistance value of the winding. The certain period of time may be measured by the timer 44. Specifically, the determination unit 363 determines whether the current value of the winding exceeds the threshold value after a certain period of time based on the increase amount of the current value of the winding per unit time. For example, the determination unit 363 may multiply the increase amount of the current value per unit time by the certain period of time and add the multiplication result to the current value based on the measurement result of the current sensor 13.

[0042] The switching unit 364 switches the control mode of the motor 10 based on the determination result of the determination unit 363. Specifically, when it is determined that the current value exceeds the threshold value, the switching unit 364 switches the control mode from the rectangular wave control mode to the PWM control mode. Also, when it is determined that the current value does not exceed the threshold value, the switching unit 364 switches the control mode from the PWM mode to the rectangular wave control mode.

[0043] Referring to FIG. 12, an example of the operation of the semiconductor device 100a will be described. Steps A to B are executed first, and steps C to E are executed at each timing determined by the timer 44.

[0044] In step A, the MCU 36a of the semiconductor device 100a acquires a preset overcurrent threshold value. The threshold value may be stored in advance in a storage device such as a memory. The threshold value corresponds to "A" in FIG. 13. The horizontal direction (horizontal axis) of FIG. 13 represents time.

[0045] Referring to FIG. 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. The curve shown by "B" in FIG. 13 can be approximated by a straight line with a certain slope. This slope corresponds to the increase amount of the current value per unit time.

[0046] Referring to FIG. 12, steps C to E may be performed only when the rotational speed of the motor 10 exceeds a predetermined speed. When the rotational speed of the motor 10 is less than the predetermined speed, the control mode of the motor 10 may be set to the PWM control mode.

[0047] In step C, the determination unit 363 of the MCU 36a determines whether each timing is included in the first period. "C" in FIG. 13 represents the first period. Steps D to E may be performed only when each timing is included in the first period.

[0048] Referring to FIG. 12, in step D, the determination unit 363 of the MCU 36a obtains a current value based on the measurement result of the current sensor 13. Referring to FIG. 13, the current value corresponding to the point indicated by "D" is obtained.

[0049] Referring to FIG. 12, in step E, the determination unit 363 determines whether the current value exceeds a threshold value by the next timing 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. When the control mode is the rectangular wave control mode and the current value exceeds the threshold value by the next timing, the switching unit 364 may switch the control mode to the PWM control mode. Also, when the control mode is the PWM control mode and the current value does not exceed the threshold value by the next timing, the switching unit 364 may switch the control mode to the rectangular wave control mode.

[0050] Embodiment 1 can prevent an overcurrent from flowing through the winding when the motor 10 rotates at a high speed and can continue the rotation of the motor 10. Further, the semiconductor device 100a can achieve miniaturization and high efficiency of the motor 10.

[0051] As described above, the invention made by the present inventor has been specifically described based on the embodiments. However, it goes without saying that the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof.

Description of Reference Numerals

[0052] 100, 100a Semiconductor devices 10 Motor 11 Target metal 12 Shaft 13 Current sensor W component 20 IPS 21 Coil pattern 22 Sensor circuit 30 Inverter 31 Insulating element 32 PMIC 33 LDO 34 IGBT 35 Gate driver 36, 36a MCU 41, 42 ADC 43 Pulse output section 44 Timer 45 CPU 361 Control section 362 Calculation section 363 Judgment section 364 Switching section

Claims

1. A determination unit that determines whether or not a current value of the winding exceeds a threshold value after a certain period of time based on at least one of an inductance value and a resistance value of the winding inside the motor; A switching unit that switches a control mode of the motor based on a determination result of the determination unit A semiconductor device comprising:

2. When it is determined that the current value exceeds the threshold value, the switching unit switches the control mode from a rectangular wave control mode to a PWM (Pulse Width Modulation) control mode The semiconductor device according to claim 1.

3. When it is determined that the current value does not exceed the threshold value, the switching unit switches the control mode from the PWM control mode to the rectangular wave control mode The semiconductor device according to claim 2.

4. A plurality of switching elements that generate a voltage applied to the winding; A gate driver that drives the gates of the respective switching elements; An IPS (Inductive Position Sensor) that measures a rotation angle of the motor; A control unit that controls the operation of the gate driver based on the control mode and the rotation angle The semiconductor device according to claim 2, comprising:

5. The determination unit determines whether or not a timing generated by a timer is within a first period during which the current value increases, and when the timing is within the first period, determines whether or not the current value exceeds the threshold value The semiconductor device according to claim 4.

6. Comprising a calculation unit that calculates an increase amount per unit time of the current value based on the inductance value and the resistance value; The determination unit determines whether or not the current value exceeds the threshold value based on a measurement result of a current sensor that measures the current value and the increase amount per unit time The semiconductor device according to claim 1.

7. When the rotation speed of the motor exceeds a predetermined speed, the determination unit determines whether or not the current value exceeds the threshold value The semiconductor device according to claim 2.

8. A determination step of determining whether or not a current value of the winding exceeds a threshold value after a certain period of time based on at least one of an inductance value and a resistance value of the winding inside the motor; A switching step of switching a control mode of the motor based on a determination result of the determination step A switching method including:

9. A determination process for determining whether a current value of the winding exceeds a threshold value after a certain period of time based on at least one of an inductance value and a resistance value of the winding inside the motor, A switching process for switching a control mode of the motor based on a determination result of the determination process A program for causing a computer to execute.

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