Motor control device and electric power steering device

Abstract

The interlock circuit (4) of the existing motor control device (13) is complex, large-sized, heavy, and costly. The motor control device (10) according to the present application includes a motor drive unit (3) that supplies current to a motor (6); a motor control unit (15) that sends a control signal to the motor drive unit; and a cut-off device (7) that is provided between the motor control unit (15) and the motor drive unit (3) and cuts off the control signal from the motor control unit (15) to the motor drive unit when the control signal deviates from a predetermined range. As a result, a large circuit is not required, abnormalities can be determined based on the output of the motor control unit (15), and the motor drive unit (3) is cut off during abnormality determination. Thus, it is possible to obtain a device that has an effective cut-off circuit while suppressing the enlargement, weight increase, and cost increase of the motor control device (10).

Description

Technical Field

[0001] The present application relates to a motor control device and an electric power steering device. Background Art

[0002] In a conventional motor control device for an electric power steering, a motor control circuit of a motor control unit issues a control signal to a motor drive unit, and the motor drive unit supplies current to a motor according to the control signal. At this time, in order to monitor an abnormal state of the motor drive unit and the motor control circuit and cut off between the motor control circuit and the motor drive unit when an abnormality is detected, an interlock circuit is provided. Here, the motor control unit is constituted by including the motor control circuit and the interlock circuit. The motor control device is constituted by the motor control unit and the motor drive unit. The interlock circuit is provided independently of the motor control circuit. The motor control circuit receives a signal from the interlock circuit and cuts off between the motor control circuit and the motor drive unit. (For example, refer to Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Laid-Open No. 1-257675 Summary of the Invention

[0006] Technical Problem to be Solved by the Invention

[0007] In a conventional motor control device, when monitoring an abnormal state of the motor drive unit and the motor control circuit and determining it to be abnormal, an interlock circuit is provided to cut off between the motor control circuit and the motor drive unit. In order to provide such an interlock circuit independently of the motor control circuit, since a monitoring circuit and a cut-off circuit are provided, the circuit scale of the motor control unit and the motor drive unit becomes complicated and large, resulting in problems such as enlargement, weight increase, and cost increase of the motor control device.

[0008] An object of the motor control device technology related to the present application is to obtain a motor control device in which a complicated and large circuit is not required, and an abnormal state of the motor drive unit and the motor control circuit can be determined based on the output of the motor control unit, and the connection between the motor control unit and the motor drive unit can be cut off at the time of abnormality determination.

[0009] Furthermore, an object is to obtain an electric power steering device including the following motor control device, in which a complicated and large circuit is not required, an abnormal state of the motor drive unit and the motor control circuit can be determined, and the motor drive unit can be cut off at the time of abnormality determination.

[0010] Technical means for solving technical problems

[0011] The motor control device involved in the present application includes:

[0012] A motor;

[0013] A motor drive unit that supplies current to the motor;

[0014] A motor control unit that sends a control signal for controlling the current supplied by the motor drive unit; and

[0015] A cut-off device that is arranged between the motor control unit and the motor drive unit and cuts off the control signal from the motor control unit to the motor drive unit when the control signal deviates from a predetermined range.

[0016] The electric power steering device involved in the present application is equipped with the above-mentioned motor control device.

[0017] Advantages of the invention

[0018] The motor control device and the electric power steering device involved in the present application do not require a large circuit such as an interlock circuit, can determine an abnormality based on the output of the motor control unit, and cut off between the motor control unit and the motor drive unit during abnormality determination. Thus, a device with an effective cut-off circuit can be obtained while suppressing the enlargement, weight increase, and cost increase of the motor control device. Description of the drawings

[0019] Figure 1 is a structural diagram of the motor control device according to Embodiment 1.

[0020] Figure 2 is a hardware structural diagram of the motor control device according to Embodiment 1.

[0021] Figure 3 is a flowchart of the main process of the cut-off device of the motor control device according to Embodiment 1.

[0022] Figure 4 is a flowchart of the initialization process of the cut-off device of the motor control device according to Embodiment 1.

[0023] Figure 5 is a flowchart of the short circuit and improper output determination process of the cut-off device of the motor control device according to Embodiment 1.

[0024] Figure 6 is a flowchart of the overcurrent determination process of the cut-off device of the motor control device according to Embodiment 1.

[0025] Figure 7It is a flowchart of the cutting process of the cutting device of the motor control device according to Embodiment 1.

[0026] Figure 8 It is a structural diagram of the motor control device according to Embodiment 2.

[0027] Figure 9 It is a flowchart of the main process of the cutting device of the motor control device according to Embodiment 2.

[0028] Figure 10 It is a flowchart of the short - circuit and improper output determination process of the cutting device of the motor control device according to Embodiment 2.

[0029] Figure 11 It is a hardware structural diagram of the motor control device according to Embodiment 3.

[0030] Figure 12 It is a structural diagram of the electric power steering device according to Embodiment 4.

[0031] Figure 13 It is a hardware structural diagram of the motor control device according to the existing example. Specific embodiments

[0032] Next, the motor control device and the electric power steering device according to the embodiments of the present application will be described with reference to the accompanying drawings.

[0033] 1. Embodiment 1

[0034] The motor control device 10 according to Embodiment 1 of the present application will be described with reference to the accompanying drawings. Figure 1 It is a structural diagram of the motor control device 10 according to Embodiment 1. Figure 2 It is a hardware structural diagram of the motor control device 10 according to Embodiment 1. Figure 3 It is a flowchart of the main process of the cutting device 7 of the motor control device 10 according to Embodiment 1. Figure 4 It is a flowchart of the initialization process of the cutting device 7 of the motor control device 10 according to Embodiment 1. Figure 5 It is a flowchart of the short - circuit and improper output determination process of the cutting device 7 of the motor control device 10 according to Embodiment 1. Figure 6 It is a flowchart of the over - current determination process of the cutting device 7 of the motor control device 10 according to Embodiment 1. Figure 7 It is a flowchart of the cutting process of the cutting device 7 of the motor control device 10 according to Embodiment 1. Figure 13 It is a structural diagram of the motor control device 13 according to the existing example.

[0035] <Existing example>

[0036] Figure 13 The motor control device 13 related to the existing example is composed of a motor control unit 17 and a motor drive unit 3. The motor control unit 17 is formed by an arithmetic processing device 1, a motor control circuit 22, and an interlock circuit 4. An input signal is input to the arithmetic processing device 1 (not shown) from the outside. The arithmetic processing device 1 calculates the current to be supplied to the motor 6 based on the input signal, outputs an instruction to the motor control circuit 22, and outputs a control signal to the motor drive unit 3 via the motor control circuit 22. The motor drive unit 3 supplies current to the motor 6 via motor connection terminals 41 and 42 according to the control signal received from the motor control circuit 22.

[0037] Figure 13 The motor drive unit 3 in it incorporates a positive-side field effect transistor (hereinafter referred to as FET) 31, FET 33, and negative-side FETs 32, 34. The positive-side FET 31 and the negative-side FET 32 are connected in series between the positive-side power supply and the negative-side power supply, and the connection point is connected to the motor connection terminal 41. The positive-side FET 33 and the negative-side FET 34 are connected in series between the positive-side power supply and the negative-side power supply, and the connection point is connected to the motor connection terminal 42. The motor connection terminals 41 and 42 are connected to the motor 6. The motor drive unit 3 is connected to the positive-side power supply and the negative-side power supply, and the negative-side power supply is grounded via the resistor of the current detection circuit.

[0038] When the motor drive unit 3 supplies current to drive the motor 6, it turns on the positive-side FET 31, turns off the negative-side FET 32, turns off the positive-side FET 33, and turns on the negative-side FET 34, thereby injecting current from the motor connection terminal 41 and sucking out current from the motor connection terminal 42. Or, it turns off the positive-side FET 31 and turns on the negative-side FET 32, turns on the positive-side FET 33 and turns off the negative-side FET 34, thereby injecting current from the motor connection terminal 42 and sucking out current from the motor connection terminal 41. Therefore, there is no situation where the positive-side FET 31 and the positive-side FET 33 are stably turned on simultaneously, or the negative-side FET 32 and the negative-side FET 34 are stably turned on simultaneously. Such an output is improper and can be determined as abnormal.

[0039] The interlock circuit 4 receives in parallel from the arithmetic processing unit 1 the content of the instruction issued by the arithmetic processing unit 1 to the motor control circuit 22. When the content of the instruction from the arithmetic processing unit 1 is inappropriate, an abnormality determination is made and a cut-off signal is output to the motor control circuit 22. For example, when the arithmetic processing unit 1 outputs an instruction to turn on both the positive-side FET 31 and the positive-side FET 33 of the motor drive unit 3 at the same time, or outputs an instruction to turn on both the negative-side FET 32 and the negative-side FET 34 of the motor drive unit 3 at the same time, the interlock circuit 4 determines that the instruction from the arithmetic processing unit 1 is inappropriate. In this case, the interlock circuit 4 outputs a cut-off signal to the motor control circuit 22, disconnecting the motor control unit 17 and the motor drive unit 3.

[0040] In addition, even when the arithmetic processing unit 1 outputs an appropriate instruction for driving the motor 6, the interlock circuit 4 determines based on the output voltage of the current detection circuit 5 whether the current flowing through the motor drive unit 3 is an overcurrent. When the output voltage of the current detection circuit 5 exceeds the overcurrent determination voltage, the interlock circuit 4 determines that an overcurrent is flowing through the motor drive unit 3 and outputs a cut-off signal to the motor control circuit 22.

[0041] In this way, the interlock circuit 4 can independently of the motor control circuit determine the abnormality of the motor control device 13 and output a cut-off signal to the motor control circuit 22, thereby cutting off the motor control unit 17 and the motor drive unit 3. Therefore, failures and deteriorations of the motor drive unit 3 and the motor 6 can be prevented.

[0042] However, in order to monitor whether the instruction output from the arithmetic processing unit 1 to the motor control circuit 22 is inappropriate, the interlock circuit 4 requires a circuit structure for separately receiving the instruction value from the arithmetic processing unit 1. In addition, in order to monitor the overcurrent of the motor drive unit 3, it is necessary to set up the current detection circuit 5, require wiring from the current detection circuit 5, and require a comparison circuit for the detected values. Furthermore, it is necessary to set up a cut-off circuit that transfers the cut-off signal from the interlock circuit 4 to the motor control circuit 22 and cuts off between the motor control circuit 22 and the motor drive unit 3.

[0043] As a result, there is the following problem in the setting of the interlock circuit 4: In order to separately set up the interlock circuit 4 from the motor control circuit 22, since it has a monitoring circuit and a cut-off circuit, the circuit scale of the motor control unit 17 and the motor drive unit 3 becomes complicated and large, leading to the enlargement, weight increase, and cost increase of the motor control device 13.

[0044] <Embodiment 1>

[0045] Figure 1 It is a structural diagram of the motor control device 10 according to Embodiment 1. Figure 1The illustrated motor control device 10 is composed of a motor control unit 15, a cut-off device 7, and a motor drive unit 3. The motor control unit 15 is formed by an arithmetic processing device 1 and a motor control circuit 20. Different from Figure 12 the conventional example shown, there is no interlock circuit 4. Instead, the cut-off device 7 is interposed between the motor control circuit 20 and the motor drive unit 3.

[0046] An input signal is input from the outside to the arithmetic processing device 1 (not shown). The arithmetic processing device 1 calculates the current to be supplied to the motor 6 based on the input signal, outputs an instruction to the motor control circuit 20, and outputs a control signal via the motor control circuit 20. The motor control circuit 20 transmits the control signal to the motor drive unit 3 via the cut-off device 7. The motor drive unit 3 supplies current to the motor 6 via motor connection terminals 41 and 42 according to the control signal received from the motor control circuit 20 via the cut-off device 7.

[0047] Figure 1 the motor drive unit 3 of Figure 13 is the same as the motor drive unit 3 related to the conventional example. The cut-off device 7 receives the output of the motor control circuit 20 and directly transmits it to the motor drive unit 3 when there is no abnormality. When there is an abnormality in the output of the motor control circuit 20, the output of the motor control circuit 20 is cut off and not transmitted to the motor drive unit 3. In addition, the input and output of the cut-off device 7 can be connected by electronic components constituting semiconductor switches such as FETs, bipolar transistors, thyristors, and ICs (Integrated Circuits), and in the case of need for cutting off, the above-mentioned electronic components are turned off to cut off the motor control unit 15 and the motor drive unit 3. The input and output of the cut-off device 7 can be connected by mechanical components such as relays, and in the case of need for cutting off, the relay is opened to cut off the motor control unit 15 and the motor drive unit 3.

[0048] Figure 1 The motor drive unit 3 in

[0049] <Improper output abnormality>

[0050] There is no situation where the positive-side FET 31 and the positive-side FET 33 of the motor drive unit 3 are simultaneously turned on, or the negative-side FET 32 and the negative-side FET 34 are simultaneously turned on. Such an output is inappropriate and can be judged as abnormal. The cut-off device 7 monitors the control signal received from the motor control circuit 20, makes an abnormality determination in the case of an inappropriate control signal, cuts off the output of the motor control circuit 20, and does not transmit it to the motor drive unit 3.

[0051] <Direct connection overcurrent abnormality>

[0052] In addition, both the positive-side FET 31 and the negative-side FET 32 connected in series in the motor drive unit 3 are cut off, or only one is turned on and the other is cut off. When both are simultaneously turned on, the motor 6 is not driven, and the FET 31 and the FET 32 are directly connected between the positive-side power supply and the negative-side power supply, and a large current flows, resulting in a failure of the motor drive unit 3. Similarly, both the positive-side FET 33 and the negative-side FET 34 connected in series are cut off, or only one is turned on and the other is cut off. When both are simultaneously turned on, the motor 6 is not driven, and the FET 33 and the FET 34 are directly connected between the positive-side power supply and the negative-side power supply, and a large current flows, resulting in a failure of the motor drive unit 3.

[0053] When the motor control unit 15 is normal, there is no situation where the positive-side FET 31 and the negative-side FET 32 of the motor drive unit 3 are stably simultaneously turned on, or the positive-side FET 33 and the negative-side FET 34 are simultaneously turned on. In this case, since an overcurrent caused by direct connection flows through the motor drive unit, when the motor control unit 15 outputs such a control signal, the cut-off device 7 determines it as an abnormality caused by direct connection overcurrent, and thus can cut off the output of the motor control circuit 20 to prevent a failure of the motor drive unit 3.

[0054] As described above, the cut-off device 7 monitors the control signal output by the motor control unit 15, determines inappropriate output abnormality and direct connection overcurrent abnormality where a large current flows, and cuts off the output of the motor control circuit 20 to prevent a failure of the motor drive unit 3. At this time, there is no need for a large-scale circuit such as the interlock circuit 4 in the prior art, the introduction of signal lines from the arithmetic processing device 1, the introduction of signal lines from the current detection circuit 5 of the motor drive unit 3, the cut-off circuit of the motor control circuit 22, and the introduction of signal lines to the cut-off circuit of the motor control circuit 22. By adopting the cut-off device 7, a motor control device with an effective cut-off circuit can be obtained while suppressing the increase in size, weight, and cost.

[0055] In Figure 1In this case, an example in which an FET is used as a switching element of the motor drive unit is shown. However, a bipolar transistor, a thyristor, and a relay may also be used to constitute the motor drive unit.

[0056] <Overcurrent abnormality>

[0057] In addition, regarding the drive of the motor 6, in most cases, the FETs 31 to 34 of the motor drive unit 3 are driven with a duty ratio to control the drive current. At this time, the on / off control of the FETs 31 to 34 is repeated, and the cut-off device 7 can calculate the motor energization current Im based on the on-time of the duty ratio control cycle. When the calculated motor energization current Im exceeds a predetermined overcurrent determination value Iov, the cut-off device 7 determines that an overcurrent is flowing abnormally. When the cut-off device 7 determines an abnormality caused by an overcurrent, the output of the motor control circuit 20 can be cut off to prevent failures of the motor drive unit 3 and the motor 6.

[0058] <Average current exceeding abnormality>

[0059] Furthermore, the cut-off device 7 accumulates the on-times of the FETs 31 to 34 of the motor drive unit 3 during the average current calculation time Tav, and divides the accumulated value by the average current calculation time Tav, thereby calculating the average motor energization current Ima during the average current calculation time Tav. When the average motor energization current Ima exceeds a predetermined average current exceeding determination value Iova, the cut-off device 7 determines that an overcurrent has been continuously flowing during the average current calculation time Tav, and thus the output of the motor control circuit 20 can be cut off to prevent a failure of the motor drive unit 3. By determining the determination value such that Iova < Iov, a value smaller than the overcurrent determination value Iov that should not be exceeded instantaneously can be determined as the average current exceeding determination value Iova that should not be continuously exceeded. Thereby, failures of the motor drive unit 3 and the motor 6, and deterioration due to an overheated state can be prevented. Iova and Iov can be obtained by calculation based on the performance of the used FET element and the impedance and reactance of the motor 6, or can be obtained through experiments.

[0060] As described above, the cutting device 7 can monitor the control signal output by the motor control unit 15 to calculate the motor energization current Im provided by the motor drive unit 3. When the motor energization current Im exceeds the overcurrent determination value Iov, it can be abnormally determined that an overcurrent is flowing, and the output of the motor control circuit 20 is cut off. In addition, the average motor energization current Ima for calculating the average value calculation time Tav is calculated, and when it exceeds the average current excess determination value Iova, it is determined that an overcurrent has continuously flowed within the average value calculation time Tav, and the output of the motor control circuit 20 is cut off. By adopting the cutting device 7, a motor control device can be obtained that does not require a large-scale circuit such as the interlock circuit 4, does not require the setting of the current detection circuit 5 and the introduction of connection lines, and has an effective cutting circuit while suppressing enlargement, weight increase, and cost increase.

[0061] <Hardware Structure of Control Device>

[0062] Figure 2 It is a hardware structure diagram of the motor control device 100 according to Embodiment 1. In the present embodiment, the hardware structure of the control device 100 is applied to the motor control unit 15 and the cutting device 7 of the motor control device 10. Each function of the control device 100 is implemented by a processing circuit included in the control device 100. Specifically, as shown in Figure 2 FIG., as a processing circuit, it includes an arithmetic processing device 90 (computer) such as a CPU (Central Processing Unit), a storage device 91 that exchanges data with the arithmetic processing device 90, an input circuit 92 that inputs external signals to the arithmetic processing device 90, and an output circuit 93 that outputs signals from the arithmetic processing device 90 to the outside.

[0063] As the arithmetic processing device 90, an ASIC (Application Specific Integrated Circuit), an IC, a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), various logic circuits, various signal processing circuits, etc. can be provided. Additionally, as the arithmetic processing device 90, multiple arithmetic processing devices of the same type or different types can also be provided, and they share the execution of each process. As the storage device 91, a RAM (Random Access Memory) configured to be able to read and write data from the arithmetic processing device 90, a ROM (Read Only Memory) configured to be able to read data from the arithmetic processing device 90, a flash memory, etc. can be provided. The input circuit 92 is connected to various sensors and switches, and includes an A / D converter, etc. that inputs the output signals of these sensors and switches to the arithmetic processing device 90. The output circuit 93 includes a drive circuit, etc. that is connected to an electrical load and converts and outputs the control signal from the arithmetic processing device 90 to these electrical loads.

[0064] Each function of the control device 100 is realized by the arithmetic processing device 90 executing software (program) stored in a storage device 91 such as a ROM and collaborating with other hardware of the control device 100 such as the storage device 91, the input circuit 92, and the output circuit 93. Additionally, setting data such as thresholds and determination values used by the control device 100 is stored in the storage device 91 such as a ROM as part of the software (program).

[0065] Figure 2 Each function of the control device 100 can be constituted by software modules respectively, or can be constituted by a combination of software and hardware.

[0066] The motor control unit 15 and the cut-off device 7 can be constituted by different control devices 100 respectively. Additionally, the motor control unit 15 and the cut-off device 7 can be constituted as different modules in the same control device. The cut-off device 7 does not have an arithmetic processing device 90 and a storage device 91, and the cut-off device 7 can be constituted to include only hardware such as logic circuits and amplifiers, integrators, sample-and-hold circuits, comparators, etc.

[0067] Hereinafter, the software processing executed when the structure of the application control device 100 is used as the hardware structure of the cut-off device 7 of the motor control device 10 according to the first embodiment will be described.

[0068] <Main Process>

[0069] Figure 3It is a flowchart of the main process executed by the arithmetic processing unit 90 of the cutoff device 7 of the motor control device 10 according to Embodiment 1. The main process of the control is executed at regular intervals (for example, every 1 ms). Here, an example of executing the main process at regular intervals is shown, but for example, the main process may also be executed using a specific signal such as a rotation angle signal of the motor as a trigger.

[0070] The arithmetic processing unit 90 starts the process in step S301 and executes the initialization process in step S400. The processing details of step S400 are shown in Figure 4 steps S401 to S419.

[0071] Next, the arithmetic processing unit 90 executes the direct connection abnormality and output improperness determination process in step S500. The processing details of step S500 are shown in Figure 5 steps S501 to S519.

[0072] Next, the arithmetic processing unit 90 executes the overcurrent determination process in step S600. The processing details of step S600 are shown in Figure 6 steps S601 to S619.

[0073] Next, the arithmetic processing unit 90 executes the cutoff process in step S700 and ends the process in step S309. The processing details of step S700 are shown in Figure 7 steps S701 to S719.

[0074] <Initialization Process>

[0075] Figure 4 It is a flowchart showing the details of the initialization process. Figure 4 Steps S401 to S419 of Figure 3 are the detailed content of step S400 of the flowchart of

[0076] The arithmetic processing unit 90 starts processing from step S401, and determines in step S402 whether the power of the cut-off device 7 has just been turned on. If the power has just been turned on, steps S403 to S410 are executed to initialize the counter and the flag. In step S403, the direct connection abnormality counter C_shrt is cleared (set to 0). Then, in step S404, the output improper abnormality counter C_ng is cleared. Then, in step S405, the overcurrent counter C_Iov is cleared. Then, in step S406, the average current excess counter is cleared. Then, in step S407, the direct connection abnormality flag f_shrt is cleared. Then, in step S408, the output improper abnormality flag f_ng is cleared. Then, in step S409, the overcurrent flag f_Iov is cleared. Then, in step S410, the average current excess flag f_Iova is cleared, and the processing ends in step S419.

[0077] In step S402, if the power of the cut-off device 7 has not just been turned on, the counter and the flag are not initialized, and the processing ends in step S419.

[0078] <Direct connection abnormality and output improper abnormality determination processing>

[0079] Figure 5 It is a flowchart showing the content of the direct connection abnormality and output improper abnormality determination processing. Figure 5 Steps S501 to S519 of Figure 3 are a flowchart showing the details of step S500 of the flowchart of

[0080] The arithmetic processing unit 90 starts processing from step S501, and determines in step S502 whether the control signal output by the motor control unit 15 is a signal that turns on both FET 31 and FET 32 simultaneously. If it is a signal that turns on both simultaneously, it is an abnormal signal that directly connects the positive power supply and the negative power supply of the motor drive unit 3 through FET 31 and FET 32, resulting in a direct connection overcurrent. Therefore, it advances to step S510, and the direct connection abnormality counter C_shrt is incremented, and the processing ends in step S519.

[0081] In step S502, if the control signal is not a signal that turns on both FET 31 and FET 32 simultaneously, it advances to step S503. In step S503, it is determined whether the control signal output by the motor control unit 15 is a signal that turns on both FET 33 and FET 34 simultaneously. If it is a signal that turns on both simultaneously, it is set as a direct connection abnormality and advances to step S510. If it is not a signal that turns on both simultaneously, it advances to step S505.

[0082] In step S505, it is determined whether the control signal output by the motor control unit 15 is a signal that turns on any one of the FETs 31 and 33 on the positive electrode side. If it is a signal that turns on any one of them, the process proceeds to step S506. If both the FET 31 and the FET 33 are turned off, the process proceeds to step S507.

[0083] In step S506, it is determined whether the control signal is a signal that turns on any one of the FETs 32 and 34 on the negative electrode side. If it is a signal that turns on any one of them, it is determined to be normal, and the process proceeds to step S508. When the control signal is a signal that turns off all of the FETs 32 and 34 on the negative electrode side, since current is not drawn while current is injected into the motor 6, it is determined that there is an improper output abnormality. The improper output abnormality counter C_ng is incremented in step S511, and the process ends in step S519.

[0084] In step S507, it is determined whether the control signal is a signal that turns on any one of the FETs 32 and 34 on the negative electrode side. If it is a signal that turns on any one of them, it becomes a signal that draws current without injecting current into the motor 6. Therefore, it is determined that there is an improper output abnormality, and the process proceeds to step S511. When the control signal is a signal that turns off all of the FETs 32 and 34 on the negative electrode side, it is determined to be normal, and the process proceeds to step S508.

[0085] In step S508, the direct connection abnormality counter C_shrt is cleared. Then, in step S509, the improper output abnormality counter C_ng is cleared. Then, the process ends in step S519.

[0086] <Overcurrent determination process>

[0087] Figure 6 It is a flowchart showing the content of the overcurrent determination process. Figure 6 Steps S601 to S619 of Figure 3 are a flowchart showing the detailed content of step S600 of the flowchart of

[0088] The process starts from step S601. In step S602, the motor energization current Im provided by the motor drive unit 3 is calculated based on the control signal output by the motor control unit 15. Regarding the drive of the motor 6, in most cases, the FETs 31 to 34 of the motor drive unit 3 are driven with a duty ratio to control the drive current. At this time, the on-off control of the FETs 31 to 34 is repeated, and the cut-off device 7 can calculate the motor energization current Im based on the on-time of the duty ratio control period. In step S603, the calculated latest motor energization current Im(n) is stored in the storage device 91. The main process is executed every 1 ms. Therefore, by sequentially storing the motor energization currents Im(1), Im(2), Im(3),..., Im(n) every 1 ms, the average value of the motor energization current Im, that is, the average motor energization current Ima, for each average value calculation time Tav can be obtained. By using a circular buffer as the storage device 91, the storage area can be used cyclically, and the averaging process can be implemented in a limited storage area. The averaging is to obtain the moving average between the latest average value calculation times Tav each time the process is executed (every 1 ms). Alternatively, the interval average can be obtained for each average value calculation time Tav.

[0089] Next, in step S604, it is determined whether the motor energization current Im is greater than the overcurrent determination value Iov. If it is greater than the overcurrent determination value Iov, the process proceeds to step S608, the overcurrent counter C_Iov is incremented, and the process ends in step S619.

[0090] If the motor energization current Im is not greater than the overcurrent determination value Iov in step S604, the process proceeds to step S605. In step S605, the motor energization current Im for the latest average value calculation time Tav is accumulated, and the accumulated value is divided by the average value calculation time Tav to calculate the average motor energization current Ima. Here, it is assumed that the average motor energization current Ima is calculated by the moving average or interval average during the average value calculation time Tav. However, it can also be calculated by a one-delay operation. Every time the average value calculation time Tav elapses, the formula Ima(n)←K×Im+(1-K)×Ima(n-1) is used for calculation. Here, K is a constant with 0<K<1. At each average value calculation time Tav, the previous average motor energization current Ima(n-1) and the latest motor energization current Im are used to obtain the current average motor energization current Ima(n). By using a one-delay operation, the memory usage amount required for the storage device 91 can be saved.

[0091] Next, in step S606, it is determined whether the average motor energization current Ima is greater than the average current excess determination value Iova. If it is greater than the average current excess determination value Iova, the average current excess counter C_Iova is incremented, and the process ends in step S619.

[0092] In step S606, when the average motor energization current Ima is not greater than the average current excess determination value Iova, the motor energization current Im is not an overcurrent, and the average motor energization current Ima does not exceed the average current. Therefore, in step S607, the overcurrent counter C_Iov is cleared, in step S608, the average current excess counter C_Iova is cleared, and the process ends in step S619.

[0093] <Cut-off process>

[0094] Figure 7 It is a flowchart showing the content of the cut-off process. Figure 7 Steps S701 to S719 of Figure 3 are a flowchart showing the detailed content of step S700 of the flowchart of

[0095] The process starts from step S701, and in step S702, it is determined whether the value of the direct connection abnormality counter C_shrt is greater than the direct connection abnormality determination time T_shrt. If it is greater than the direct connection abnormality determination time T_shrt, it is determined that there is a direct connection abnormality, and the process proceeds to step S706, and the direct connection abnormality flag f_shrt is set (input 1). Then, the direct connection abnormality storage flag f_shrtM set in the non-volatile storage device that was not cleared in the initialization process is set. Then, in step S710, the motor drive unit 3 is disconnected from the motor control unit 15, and the process ends in step S719.

[0096] In step S702, when the value of the direct connection abnormality counter C_shrt is not greater than the direct connection abnormality determination time T_shrt, the process proceeds to step S703. In step S703, it is determined whether the value of the output improper abnormality counter C_ng is greater than the output improper abnormality determination time T_ng. If it is greater than the output improper abnormality determination time T_ng, it is determined that there is an output improper abnormality, and the process proceeds to step S707. In step S707, the output improper abnormality flag f_ng is set. Then, the output improper abnormality storage flag f_ngM set in the non-volatile storage device that was not cleared in the initialization process is set, and the process proceeds to step S710.

[0097] In step S703, when the value of the output malfunction counter C_ng is not greater than the output malfunction determination time T_ng, proceed to step S704. In step S704, determine whether the value of the overcurrent counter C_Iov is greater than the overcurrent determination time T_Iov. If it is greater than the overcurrent determination time T_Iov, determine that overcurrent is determined, and proceed to step S708. In step S708, set the overcurrent flag f_Iov. Then, set the overcurrent storage flag f_IovM set in the non-volatile storage device that was not cleared in the initialization process, and proceed to step S710.

[0098] In step S704, when the value of the overcurrent counter C_Iov is not greater than the overcurrent determination time T_Iov, proceed to step S705. In step S705, determine whether the value of the average current exceed counter C_Iova is greater than the average current exceed time T_Iova. If it is greater than the average current exceed time T_Iova, determine that the average current exceeds the determination, and proceed to step S709. In step S709, set the average current exceed flag f_Iova. Then, set the average current exceed storage flag f_IovaM set in the non-volatile storage device that was not cleared in the initialization process, and proceed to step S710.

[0099] In step S705, when the value of the average current exceed counter C_Iova is not greater than the average current exceed time T_Iova, proceed to step S719 and end the process. The values of the direct connection abnormality determination time T_shrt, the output malfunction determination time T_ng, the overcurrent determination time T_Iov, and the average current exceed time T_Iova can be set by experiments or on-board calculations to be suitable for abnormality determination times.

[0100] With the structure described above, the function of the cutoff device 7 can be implemented by software. Thus, an effective cutoff device 7 can be obtained while suppressing the increase in size, weight, and cost of the motor control device 10. In addition, when the cutoff process is performed, by storing each flag indicating the cause of the cutoff in the non-volatile storage device, it is easy to conduct a postmortem investigation.

[0101] 2. Embodiment 2

[0102] Refer to the drawings to describe the motor control device 11 according to Embodiment 2 of the present application. Figure 8 It is a structural diagram of the motor control device 11 according to Embodiment 2. Figure 9 It is a flowchart of the main process of the cutoff device 71 of the motor control device 11 according to Embodiment 2. Figure 10It is a flowchart of the short - circuit and output improper determination process of the cut - off device 71 of the motor control device 11 according to Embodiment 2.

[0103] <Structure>

[0104] In Embodiment 1, the motor 6 connected to two connection terminals 41 and 42 is illustrated, but the number of terminals to which the motor is connected is not limited to two. In Embodiment 2, as Figure 8 shown, an example applied to a three - phase AC motor 61 connected to three connection terminals 41, 42, and 43 is shown. Relative to Figure 1 the structure diagram, in Figure 8 the motor drive unit 39 supplies current to the three - phase AC motor 61 from the three connection terminals 41, 42, and 43, and this three - phase AC motor 61 includes six FETs 31 to 36. The motor control circuit 21 outputs control signals to the six FETs 31 to 36 according to the instructions of the arithmetic processing device 101.

[0105] The cut - off device 71 is provided between the motor control unit 16 and the motor drive unit 39, receives the control signal from the motor control unit 16, and outputs it to the motor drive unit 39. Various abnormalities are detected according to the control signal, and when an abnormality occurs, the motor drive unit 39 is cut off from the motor control unit 16.

[0106] The software processing executed when the structure of the control device 100 is applied to the structure of the cut - off device 71 will be described.

[0107] <Main processing>

[0108] Figure 9 It is a flowchart of the main processing executed by the arithmetic processing device 90 of the cut - off device 71 of the motor control device 11 according to Embodiment 2. The main processing of the control is executed at regular intervals (for example, every 1 ms). Here, an example of executing the main processing at regular intervals is shown, but for example, the main processing can also be executed triggered by a specific signal such as the rotation angle signal of the motor.

[0109] The arithmetic processing device 90 starts the processing in step S901 and executes the initialization processing in step S400. The processing content of step S400 is the same as that in Embodiment 1 and is shown in steps S401 to S419 in Figure 4 ...

[0110] Next, the arithmetic processing device 90 executes the direct - connection abnormality and output improper abnormality determination processing in step S1000. The processing content of step S1000 is shown in steps S1001 to S1019 in Figure 10 ...

[0111] Next, the arithmetic processing unit 90 executes overcurrent determination processing in step S600. The processing content of step S600 is the same as that of the first embodiment, and is shown in steps S601 to S619 of Figure 6 .

[0112] Next, the arithmetic processing unit 90 executes a cut-off process in step S700 and ends the process in step S909. The processing content of step S700 is the same as that of the first embodiment, and is shown in steps S701 to S719 of Figure 7 .

[0113] <Direct connection abnormality, output improper abnormality determination processing>

[0114] Figure 10 is a flowchart showing the content of the direct connection abnormality and output improper abnormality determination processing. Figure 10 Steps S1001 to S1019 of Figure 9 are a flowchart showing the detailed content of step S1000 of the flowchart of

[0115] Compared with steps S501 to S519 of the flowchart of the first embodiment Figure 5 , Figure 10 the differences in the flowchart of

[0116] are that as the number of FETs increases from 4 to 6, step S1004 is added, and the number of FETs to be determined in steps S1005, S1006, and S1007 increases by 1 each compared to steps S505, S506, and S507.

[0117] The arithmetic processing unit 90 starts processing from step S1001, and in step S1002, it determines whether the control signal output by the motor control unit 16 is a signal that turns on FET 31 and FET 32 simultaneously. If it is a signal that turns on simultaneously, it is an abnormal signal that directly connects the positive power supply and the negative power supply of the motor drive unit 3 through FET 31 and FET 32, resulting in a direct connection overcurrent. Therefore, it proceeds to step S1010, and an addition operation is performed on the direct connection abnormality counter C_shrt, and the process ends in step S1019.

[0117] In step S1002, when the control signal is not a signal that turns on FET 31 and FET 32 simultaneously, it proceeds to step S1003. In step S1003, it determines whether the control signal output by the motor control unit 16 is a signal that turns on FET 33 and FET 34 simultaneously. If it is a signal that turns on simultaneously, it is set as a direct connection abnormality, and it proceeds to step S1010. If it is not a signal that turns on simultaneously, it proceeds to step S1004.

[0118] In step S1003, when the control signal is not a signal that turns on FET 33 and FET 34 simultaneously, proceed to step S1004. In step S1004, determine whether the control signal output by the motor control unit 16 is a signal that turns on FET 35 and FET 36 simultaneously. If it is a signal for simultaneous conduction, it is set as a direct connection abnormality, and proceed to step S1010. If it is not a signal for simultaneous conduction, proceed to step S1005.

[0119] In step S1005, determine whether the control signal output by the motor control unit 16 is a signal that turns on any one of the positive-side FETs 31, 33, and 35. If it is a signal that turns on any one of them, proceed to step S1006. If all of FET 31, FET 33, and FET 35 are turned off, proceed to step S1007.

[0120] In step S1006, determine whether the control signal is a signal that turns on any one of the negative-side FETs 32, 34, and 36. If it is a signal that turns on any one of them, it is determined to be normal, and proceed to step S1008. When the control signal is a signal that turns off all of the negative-side FETs 32, 34, and 36, it is determined as an improper output abnormality. In step S1011, perform an addition operation on the improper output abnormality counter C_ng, and end the process in step S1019.

[0121] In step S1007, determine whether the control signal is a signal that turns on any one of the negative-side FETs 32, 34, and 36. If it is a signal that turns on any one of them, it is determined as an improper output abnormality, and proceed to step S1011. When the control signal is a signal that turns off all of the negative-side FETs 32, 34, and 36, it is determined to be normal, and proceed to step S1008.

[0122] In step S1008, clear the direct connection abnormality counter C_shrt. Then, in step S1009, clear the improper output abnormality counter C_ng. Then, end the process in step S1019.

[0123] As described above, the case where the motor 61 is a three-phase AC motor has been described. Even when the motor is connected to a number of terminals other than two or three of the motor drive unit, has a number of phases other than two or three, or is a DC motor instead of an AC motor, the abnormal determination and cut-off processing of the control signal of the cut-off device of the present application can be applied.

[0124] 3. Embodiment 3

[0125] The motor control device 12 according to Embodiment 3 of the present application will be described with reference to the accompanying drawings. Figure 11 It is a hardware configuration diagram of the motor control device 12 according to Embodiment 3.

[0126] Figure 11 It shows the structure after further adding the cut-off device 7 to the Figure 13 motor control device 13 of the existing example. Figure 11 Among them, the difference from the existing example is that a cut-off device 7 is provided between the motor control unit 17 including the interlock circuit 4 and the motor drive unit 3.

[0127] Without changing the structure of the existing example, the redundancy of the cut-off function for the abnormality of the motor control device is expanded only by adding the cut-off device 7. With this structure, dual monitoring of the detection and cut-off of the abnormality of the motor control device 12 can be implemented. Therefore, since the cut-off device 7 can be added without changing the existing motor control device, the expansion of redundancy can be simply achieved in a small scale, lightweight, and low cost, which is of great significance.

[0128] 4. Embodiment 4

[0129] Figure 12 It is a structure diagram of the electric power steering device 150 according to Embodiment 4. In Figure 12 this, an example in which the motor control device 10 and the motor 6 are applied to the electric power steering device 150 mounted on a vehicle will be described. Figure 12 The electric power steering device 150 of this is an example of a rack-type electric power steering device. The electric power steering device 150 according to Embodiment 4 also uses the motor control devices 11 and 12 in addition to the motor control device 10, and also uses the motor 61 in addition to the motor 6, and still has the same effect.

[0130] If the driver generates a steering torque in the steering mechanism of the vehicle by turning the steering wheel 151, the torque sensor 152 detects the steering torque and outputs it to the motor control device 10. In addition, the speed sensor 153 detects the traveling speed of the vehicle and outputs it to the motor control device 10. The motor control device 10 drives the motor 6 based on the inputs from the torque sensor 152 and the speed sensor 153 to generate an auxiliary torque for the auxiliary steering torque, and supplies it to the steering mechanism of the front wheels 154 of the vehicle. Regarding the torque sensor 152 and the speed sensor 153, the description is omitted in Figure 1 this. The motor control device 10 can drive the motor 6 and generate an auxiliary torque based on inputs other than the torque sensor 152 and the speed sensor 153.

[0131] Since the motor control device 10 applied to the electric power steering device can perform an effective cut-off process in case of abnormality, and at the same time can suppress the enlargement, weight increase, and cost increase of the motor control device 10, it can contribute to the miniaturization, light weight, and cost reduction of the entire electric power steering device.

[0132] Although this application describes various exemplary embodiments and examples, the various features, methods, and functions described in one or more embodiments are not limited to the application of a specific embodiment, and can be applied to the embodiments individually or in various combinations. Therefore, it can be considered that countless unillustrated variations are also included in the technical scope disclosed in the specification of this application. For example, it is assumed to include cases where at least one component is deformed, added, or omitted, and cases where at least one component is extracted and combined with components of other embodiments.

[0133] Reference numeral description

[0134] 3, 39 Motor drive unit, 4 Interlock circuit, 5 Current detection circuit, 6, 61 Motor, 7, 71 Cut-off device, 10, 11, 12, 13 Motor control device, 15, 16, 17 Motor control unit, 31, 32, 33, 34, 35, 36 FET, 150 Electric power steering device.

Claims

1. A motor control device, characterized in that, Comprising: A motor; A motor driving unit, which includes a plurality of positive-side switching elements connected to the positive side of a DC power supply, a plurality of negative-side switching elements connected to the negative side of the DC power supply, and output terminals provided at each connection point of a connection point where one of the positive-side switching elements and one of the negative-side switching elements are connected in series, and supplies current to the motor from the output terminals; A motor control unit, which sends a control signal for controlling the current supplied by the motor driving unit by performing duty ratio control of turning on and off the positive-side switching elements and the negative-side switching elements of the motor driving unit respectively; And A cut-off device, which is arranged between the motor control unit and the motor driving unit, calculates the current value flowing from the motor driving unit to the motor based on the conduction time of the control signal in the duty ratio control cycle, and cuts off the control signal from the motor control unit to the motor driving unit when the calculated current value exceeds a predetermined over-current determination value.

2. A motor control device, characterized in that, Comprising: A motor; A motor driving unit, which includes a plurality of positive-side switching elements connected to the positive side of a DC power supply, a plurality of negative-side switching elements connected to the negative side of the DC power supply, and output terminals provided at each connection point of a connection point where one of the positive-side switching elements and one of the negative-side switching elements are connected in series, and supplies current to the motor from the output terminals; A motor control unit, which sends a control signal for controlling the current supplied by the motor driving unit by performing duty ratio control of turning on and off the positive-side switching elements and the negative-side switching elements of the motor driving unit respectively; And A cut-off device, which is arranged between the motor control unit and the motor driving unit, accumulates the conduction time of the control signal during a predetermined average value calculation time, calculates the average current based on the value obtained by dividing the accumulated value by the average value calculation time, and cuts off the control signal when the calculated average current exceeds a predetermined average over-current determination value.

3. A motor control device, characterized in that, Comprising: A motor; A motor driving unit, which includes a plurality of positive-side switching elements connected to the positive side of a DC power supply, a plurality of negative-side switching elements connected to the negative side of the DC power supply, and output terminals provided at each connection point of a connection point where one of the positive-side switching elements and one of the negative-side switching elements are connected in series, and supplies current to the motor from the output terminals; A motor control unit, which sends a control signal for controlling the current supplied by the motor driving unit; And A cutting device that cuts off the control signal when the state where one of the positive-side switching elements and one of the negative-side switching elements connected in series are simultaneously turned on by the control signal lasts for more than a first determination time, and cuts off the control signal when the state where any one of the positive-side switching elements is turned on and all of the negative-side switching elements are turned off, or any one of the negative-side switching elements is turned on and all of the positive-side switching elements are turned off by the control signal lasts for more than a second determination time.

4. The motor control device according to any one of claims 1 to 3, characterized in that the motor control unit further includes an interlock circuit that cuts off the control signal from the motor control unit to the motor drive unit when the control signal deviates from a predetermined range.

5. The motor control device according to claim 4, characterized in that the motor drive unit has a current detection circuit that detects the current value flowing through the motor drive unit, and when the current value detected by the current detection circuit exceeds an overcurrent interlock determination value, the interlock circuit cuts off the control signal.

6. The motor control device according to any one of claims 1 to 3, characterized in that the cutting device cuts off the control signal through a semiconductor switch.

7. The motor control device according to any one of claims 1 to 3, characterized in that the cutting device cuts off the control signal through a mechanical relay.

8. An electric power steering device, characterized in that it includes the motor control device according to any one of claims 1 to 7.

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