JP7326822B2 - motor controller - Google Patents

Description

The present invention relates to a motor control device.

Vehicles such as electric vehicles (EV), hybrid vehicles (HEV, PHEV), trains, etc. equipped with a motor as a power source for running have an angular position detector for detecting the rotation angle (angle in the direction of rotation) position of the motor. A device is provided. A rotational angular position (hereinafter referred to as "angular position") detected by the angular position detector is mainly used to control the motor. The angular position detection device is composed of a resolver attached to the rotating shaft of a motor, and an RDC (Resolver to Digital Converter) that converts an analog output signal from the resolver into digital angle information.

Patent Literature 1 describes a fault diagnosis method for an RDC built in a control microcomputer (hereinafter “built-in RDC”). A control microcomputer disclosed in Patent Document 1 includes an RDC and a motor control section. The RDC includes an angle detector that generates the rotation angle of the motor based on the detection signal input from the resolver, and an encoder that encodes the rotation angle input from the angle detector. Based on the rotation angle, the encoder outputs a forward rotation signal FD that generates a pulse each time the rotation angle increases, a reverse rotation signal RD that generates a pulse each time the rotation angle decreases, and a rotation angle that is a reference angle. A reference angle signal NM is generated such that a pulse is generated each time (for example, θ=0). These generated signals are transmitted to a monitoring microcomputer that monitors the operation of the control microcomputer. The monitoring microcomputer executes monitoring control processing based on these signals (FD, RD, NM), thereby determining whether or not the motor is normally controlled by the angle detection unit of the control microcomputer. .

JP 2014-17932 A

In order to comply with functional safety such as IEC61508, which is an international safety standard, and ISO26262, which is a functional safety standard for automobiles, for example, when assuming a safety goal such as "no unintended sudden acceleration or sudden deceleration, However, in the case of an RDC (hereinafter referred to as "external RDC") provided outside the control microcomputer, the external RDC and the motor control unit must be able to detect the failure of the angle detection unit immediately. A data bus connection can be selected for transmitting the angular position information (information indicating the rotational angular position) generated in step 1 to the motor control section. If an abnormality such as disconnection or short circuit occurs in this data bus, the conventional technology having a built-in RDC failure diagnosis function cannot diagnose a failure of the external RDC caused by the data bus abnormality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor control device that enables failure diagnosis of an external RDC.

In order to solve the above-described problems and achieve the object, a motor control device according to the present invention provides angular position information indicating the rotational angular position of a motor, based on a rotation detection signal corresponding to the rotational angle of the motor, and A resolver digital converter for generating a Z-phase pulse that is output once per rotation, and a data bus connected to the resolver digital converter for transmitting the angular position information. A motor control device is connected to the resolver digital converter, and based on the angular position information and the Z-phase pulse input via a signal line for transmitting the Z-phase pulse and the data bus and the signal line, the Stores an abnormality determination unit that determines whether or not at least one of the resolver digital converter and the data bus is abnormal, and an error determination table that associates an angular position detection error including an angular position detection error range with the number of revolutions of the motor. and a storage unit, wherein the abnormality determination unit stores the angular position detection error range obtained by referring to the error determination table when the rise of the Z-phase pulse is detected, and the rotational angular position Based on the above, the presence or absence of the abnormality is determined.

According to the present invention, it is possible to diagnose the failure of an external RDC.

1 is a diagram showing a configuration example of a motor control device 100 according to an embodiment of the present invention; FIG. FIG. 2 is a diagram showing a configuration example of the RDC 2 and the processing unit 5 shown in FIG. 1; FIG. 4 is a diagram showing angular position information transmitted to the data bus 3 and the timing at which the Z-phase pulse is input; A diagram showing the correspondence relationship between the angular position detection error and the number of revolutions A diagram showing the TN (torque-rotational speed) characteristics of the motor 300 A diagram showing an example of an angular position detection error calculated in advance Flowchart for explaining the processing operation until the detection error allowable value 53b is set A flow chart for explaining a processing operation for diagnosing disconnection or the like of the data bus 3 using the detection error tolerance 53b. A diagram showing a configuration example according to a comparative example of the motor control device 100 according to the present embodiment.

A motor control device according to an embodiment of the present invention will be described in detail below with reference to the drawings. In addition, this invention is not limited by this embodiment.

Embodiment FIG. 1 is a diagram showing a configuration example of a motor control device 100 according to an embodiment of the present invention. Motor control device 100 is an example of a power conversion device that converts DC power supplied from battery 200 into AC power and supplies the AC power to motor 300 . The motor 300 is a synchronous rotating electric machine, an induction rotating electric machine, or the like that generates driving force for running a vehicle such as an EV.

The motor control device 100 includes an inverter, a resolver 1, an RDC 2, a processing section 5, and a gate drive circuit 6.

Inverter 7 converts the DC voltage output from battery 200 into a three-phase AC voltage, and applies the converted three-phase AC voltage to motor 300 to drive motor 300 . The inverter 7 includes a plurality of switching elements such as IGBTs (insulated gate bipolar transistors). The switching element performs a switching operation according to a gate drive signal input from the gate drive circuit 6 . Note that the switching element is not limited to an IGBT, as long as it is an element capable of performing a switching operation in response to a gate drive signal. The gate drive signal is a signal obtained by amplifying each of the U-phase, V-phase, and W-phase pulse width modulation signals to a voltage value capable of driving the switching element. The gate drive signal is a rectangular wave signal that takes a binary value of H level or L level.

The gate drive circuit 6 generates gate drive signals corresponding to the U, V and W phases based on the respective pulse width modulation signals of the U, V and W phases input from the processing unit 5. do. Details of the processing unit 5 will be described later.

The resolver 1 includes a stator and a rotor, and is a rotation angle sensor that outputs a signal corresponding to a change in reluctance between the rotor and the stator (corresponding to the rotation angle of the motor 300) as a resolver signal.

The resolver signal includes two rotation detection signals. The two rotation detection signals vary in amplitude sinusoidally according to the rotation angle (rotation angle θ) of the motor 300, and are out of phase with each other by an electrical angle of 90°. One rotation detection signal is a waveform signal (=ref·sin θ) obtained by amplitude-modulating the excitation signal ref with sin θ. The other rotation detection signal is a waveform signal (=ref·cos θ) obtained by amplitude-modulating the excitation signal ref with cos θ. The excitation signal ref is a constant frequency signal supplied to the primary coil of the resolver 1 . By supplying the excitation signal ref to the primary coil of the resolver 1 , the above two rotation detection signals are obtained from each of the secondary coils of the resolver 1 .

The RDC 2 generates angular position information based on the resolver signal input from the resolver 1 and inputs it to the data bus 3 , and further generates a Z-phase pulse based on the resolver signal and inputs it to the signal line 4 . Angular position information and Z-phase pulses are incremental encoder pulses.

Next, a configuration example of the RDC 2 and the processing unit 5 will be described with reference to FIG. FIG. 2 is a diagram showing a configuration example of the RDC 2 and the processing unit 5 shown in FIG.

The RDC 2 has an angle detector 21 and an encoder 22 .

The angle detection unit 21 supplies an excitation signal ref to the resolver 1 and receives a resolver signal output from the resolver 1 in response to the excitation signal ref. The angle detector 21 generates angular position information indicating the rotational angular position of the motor 300 from the input resolver signal. The angle resolution M [bit] of the angle detection unit 21 is, for example, 12 bits. Note that the angle resolution of the angle detection unit 21 is not limited to 12 bits. In this embodiment, for convenience of explanation, a configuration example in which the angular resolution of the angle detection unit 21 is 12 bits will be explained.

When the motor 300 is rotating in the positive direction (normal rotation), the angular position information from the angle detection unit 21 increases from 0 to 4095 during one rotation, and returns from 4095 to 0 again after one rotation. . When the motor 300 is rotating in the reverse direction (reverse rotation), the angular position information from the angle detection unit 21 decreases from 4095 to 0, and returns from 0 to 4095 after one rotation.

The encoder 22 encodes the angular position information input from the angle detection section 21 into a Z-phase pulse, and transmits the Z-phase pulse to the processing section 5 via the signal line 4 . The Z-phase pulse is a signal called "North Marker (NM)" that is output each time the motor 300 makes one revolution (one electrical angle revolution). Specifically, the Z-phase pulse is a binary signal that is normally "0" (L level) and "1" (H level) when the rotation angle is zero. The H-level Z-phase pulse is generated during the period of "0" each time the rotation angle becomes "0".

The processing unit 5 includes a motor control unit 51 that generates a pulse width modulated signal based on the angular position information, an abnormality determination unit 52 that performs abnormality determination based on the Z-phase pulse, and a storage unit 53 . The processing unit 5 is composed of a CPU (Central Processing Unit), and a motor control unit 51 and an abnormality determination unit 52 are realized by installing a predetermined program in the CPU.

The motor control unit 51 calculates the number of revolutions (rotational speed) of the motor 300 from the change per unit time of the angular position information input from the angle detection unit 21, for example. Based on a target torque input from a host ECU (Electronic Control Unit) (not shown), the motor control unit 51 generates a pulse width modulation signal, which is a control signal for causing the motor 300 to generate torque indicated by the target torque. It is generated and output to the gate drive circuit 6 . The host ECU is a processor that controls the vehicle in a centralized manner. At this time, the motor control unit 51 detects three currents flowing through the motor 300 based on at least two (for example, U-phase and W-phase current detection signals) of current detection signals detected by a plurality of current sensors (not shown). The pulse width modulation signal is feedback-controlled to the gate drive circuit 6 so that each phase current has a target value corresponding to the target torque. A plurality of current sensors are provided in the three-phase wiring that supplies current from the inverter 7 to the motor 300, and are sensors that detect the current of each phase. Calculations in feedback control are performed in a dq-axis rotating coordinate system. That is, the motor control unit 51 calculates the current command values for each of the dq axes according to the input target torque, and coordinates each phase current detection signal from the current sensor to the actual current value of the two phases (dq axes). Convert. Then, the motor control unit 51 generates a control signal to the gate drive circuit 6 by feedback control based on the current command value after the coordinate conversion and the actual current value. Angular position information and the number of revolutions are required during the coordinate conversion described above and during control signal generation by feedback control.

The abnormality determination unit 52 determines that the angular position acquired when the Z-phase pulse is detected (when the potential of the signal line 4 changes from the L level to the H level) is within the detection error tolerance value 53b stored in the storage unit 53. or not. The detection error allowable value 53b is information indicating the allowable range of angular position detection error. A specific example of the detection error tolerance 53b will be described later.

As a result of the comparison, if the angular position when the Z-phase pulse is detected is within the detection error tolerance 53b, the abnormality determination unit 52 determines that the angular position is a normal value. etc. have not occurred. If the angular position when the Z-phase pulse is detected exceeds the detection error tolerance 53b as a result of the comparison, the abnormality determination unit 52 determines that the angular position is an abnormal value. It is determined that there is a failure of

Next, the operation of motor control device 100 according to the present embodiment will be described with reference to FIGS. 3 to 8. FIG. FIG. 3 is a diagram showing angular position information transmitted to the data bus 3 and the timing at which the Z-phase pulse is input. FIG. 3A shows Z-phase pulses and the like when the motor is rotating at a low speed. FIG. 3B shows Z-phase pulses and the like when the motor rotates at medium speed.

"nCS" means an output of an active-low "Chip Select terminal" provided in RDC2. "n" means negative logic. "nCS" is a terminal for designating which element is to be read or written. "nRD" means the output of an active-low "Read terminal" provided in RDC2. "n" means negative logic. "nRD" is a terminal for reading angular position information in RDC2. The RDC 2 outputs angular position information to the data bus 3 when both nCS and nRD become L level (active).

The abnormality determination unit 52 can read the angular position information transmitted to the data bus 3 when the "interrupt response time" has elapsed (timing t2) from the time when the Z-phase pulse was input (timing t1). Since the interrupt response time is a fixed value determined by the performance of the processor that constitutes the processing unit 5, the interrupt response times shown in FIGS. 3(a) and 3(b) are the same value. In the example of FIG. 3A, the change in angular position (angular velocity) is detected once during the interrupt response time, whereas in the example of FIG. The change in angular position (angular velocity) detected is 5 times. Since the change in angular position (angular velocity) depends on the rotation speed of the motor 300 in this way, the angular position detection error increases as the motor rotation speed increases.

This angular position detection error will be described with a specific example.

If the motor rotation speed is 10 rps (10 rotations in 1 s) and this 10 rps rotation speed is detected by the processing unit 5 with a resolution of 12 bits (angular positions 0 to 4095), then 1 s/10 r/(2^12)= At 24414 ns, it rotates by 1/4096. When the interrupt response time is 10 us, the value obtained by dividing the response time by the time per 1/4096 rotation (24414 ns) is 10000 ns/24414 ns=0.4096. Since the angular position is represented by an integer, it is shifted by one as shown in FIG. 3(a). That is, the angular positions are shifted by 1/4096 of a turn.

If the motor rotation speed is 100 rps (100 rotations per second) and this 100 rps rotation speed is detected with a resolution of 12 bits (angular position 0 to 4095), then 1 s/100 r/(2^12) = 2441.4 ns , is rotated by 1/4096. When the interrupt response time is 10 us, the value obtained by dividing the response time by the time per 1/4096 rotation (2441.4 ns) is 10000 ns/2441.4 ns=4.096. Since the angular position is represented by an integer, it is shifted by 5 as shown in FIG. 3(b). That is, the angular positions are shifted by 5/4096 turns.

FIG. 4 shows the relationship between the angular position error (angular position detection error) derived in this way and the rotational speed. FIG. 4 is a diagram showing the correspondence relationship between the angular position detection error and the number of revolutions. The horizontal axis is the rotation speed, and the vertical axis is the angular position detection error.

As described above, the resolution of the processing unit 5 expresses the angular position as an integer, so the angular position detection error has a staircase pattern (discrete values) as shown in FIG. Since the motor 300 operates while repeating acceleration and deceleration, angular position detection errors do not occur uniformly with respect to the number of revolutions as shown in FIG. Therefore, the impact is small.

FIG. 5 is a diagram showing TN (torque-rotational speed) characteristics of the motor 300. As shown in FIG. The horizontal axis in FIG. 5 is the number of revolutions, and the vertical axis is torque.

The motor 300 can realize characteristics close to those of the principle model A. However, in the motor 300 for EV, the current may be limited in order to prevent damage due to heat generation. torque-rotation characteristics). Therefore, the actual characteristics of the motor 300 are set as shown in B. FIG. Therefore, the angular position detection error varies depending on the system and speed range. Taking this into consideration, for example, in the motor control device 100, the position detection value using the Z-phase pulse at the time of maximum acceleration, maximum deceleration, etc. is obtained in advance, so that the angle A position detection error can be calculated.

An example of the angular position detection error calculated in advance is shown in FIG. FIG. 6 is a diagram showing an example of an angular position detection error calculated in advance. As shown in FIG. 6, the angular position detection error includes an angular position detection error range. In FIG. 6, for convenience of explanation, the angular position detection error is similar to the principle model A shown in FIG. 5, but the angular position detection error may be modeled on the characteristic B shown in FIG.

The angular position detection error range is set in advance as a value having a certain width with respect to the angular position detection error that varies depending on the number of revolutions (rotational speed). The angular position detection error range is set in consideration of, for example, the manufacturing tolerance of the motor control device 100, usage environment conditions, power consumption, driving time, and the like. Information that associates the angular position detection error, including the angular position detection error range, with the number of revolutions is pre-stored in the storage unit 53 as an error determination table 53a. The angular position detection error range is equal to the permissible value (detection error permissible value 53b) indicating the permissible range of the angular position detection error. The detection error tolerance 53b is a judgment value for judging whether or not there is an abnormality in the angular position. In other words, the detection error allowable value 53b is a judgment value for judging whether disconnection of the data bus 3, failure of the external RDC 2, or the like has occurred.

If the angular position is within the detection error tolerance 53b, it can be determined that there is no disconnection of the data bus 3 or failure of the external RDC 2. FIG. If the angular position exceeds the detection error tolerance 53b, it can be determined that the data bus 3 is broken or the external RDC 2 is out of order.

Next, referring to FIGS. 7 and 8, the operation for determining whether or not there is a disconnection of the data bus 3 or a failure of the external RDC 2 will be described.

FIG. 7 is a flow chart for explaining the processing operations until the detection error tolerance 53b is set.

As shown in FIG. 7, during normal motor control, the processing unit acquires an angular position (angular position information) at a cycle of 100 us (step S1).

At this time, the processing unit 5 calculates the difference between the angular position acquired last time and the angular position acquired this time, and divides this difference by the time T to calculate the latest angular velocity (current angular velocity) (step S2).

Thereafter, the processing unit 5 refers to the error determination table 53a stored in advance in the storage unit 53, and calculates the latest angular position detection error range corresponding to the current angular velocity (step S3). In this manner, the processing unit 5 continues to calculate the latest angular position detection error range in a cycle of 100 us while the motor is being controlled.

The calculated latest angular position detection error range is stored in the storage unit 53 in chronological order as the detection error allowable value 53b (step S4).

FIG. 8 is a flow chart for explaining the processing operation for diagnosing disconnection of the data bus 3 using the detection error tolerance 53b.

In step S11, the abnormality determination unit 52 determines whether or not the rise of the Z-phase pulse has been detected (step S11).

When the rise of the Z-phase pulse is detected (step S11: Yes), the abnormality determination unit 52 acquires the latest angular position (step S12), and stores the acquired angular position in the storage unit 53 in step S4. is compared with the detected error tolerance 53b.

As a result of the comparison, if the angular position is within the detection error tolerance 53b (step S13: Yes), the abnormality determination unit 52 determines that the angular position is a normal value (step S14).

As a result of the comparison, if the angular position exceeds the detection error tolerance 53b (step S13: No), the abnormality determination unit 52 determines that the angular position is an abnormal value. It is determined that it is (step S15).

For example, when each bit of the data bus 3 is stuck to the high side, that is, when each bit of the data bus 3 is all "1", there is a possibility that the data bus 3 is short-circuited.

In some cases, each bit of the data bus 3 is fixed to the low side, but this is the case in the signal transmission path (data bus 3, substrate wiring pattern, package terminal, bonding wire, etc.) from the RDC 2 to the processing unit 5, for example. , disconnection, poor contact, etc. may occur. Even if each bit of the data bus 3 is stuck on the low side in this way, there is no problem because an abnormality in the angular position can be diagnosed by monitoring the change on the high side with software. The reason for this is that there is a tendency that the more significant the most significant bit (MSB) side of the angle position, the longer the change time. For example, at a relatively safe low speed such as 10rps, 1s/10r/(2^12)=24.414us rotates by 1/4096, so 8/4096 (=1000b) is 195us. . This level is sufficiently detectable even by a motor control system that detects positions at intervals of about 100 us. In this case, it can be seen that it is easy to find the high-side change of the upper [11:3]. That is, the lower 3 bits ([2:0]) on the LSB side change rapidly, but the upper 8 bits ([11:3]) on the MSB side change relatively slowly at a detectable level. It is easy to find the high-side change of the upper 8 bits of . [11:3] represents the upper 8 bits on the MSB side of the 12-bit data bus 3 .

FIG. 9 is a diagram showing a configuration example according to a comparative example of the motor control device 100 according to this embodiment. A motor control device 100A shown in FIG. 9 includes an RDC 2A and a processing section 5A instead of the RDC 2 and processing section 5 shown in FIG. RDC2A is an external RDC, like RDC2 shown in FIG. The processing unit 5A does not include the abnormality determination unit 52 and storage unit 53 shown in FIG. Also, the motor control device 100A does not include the signal line 4 shown in FIG.

According to the motor control device 100A, although the angular position information can be transmitted to the processing unit 5A through the data bus 3, since the Z-phase pulse cannot be used, each bit of the data bus 3 is fixed to the high side or the low side. Even if the external RDC2A is connected, the failure cannot be determined. Therefore, in the motor control device 100A according to the comparative example provided with the external RDC 2A, it is necessary to clear the safety goals for complying with functional safety such as IEC61508, which is an international safety standard, and ISO26262, a functional safety standard for automobiles. is difficult.

On the other hand, motor control device 100 according to the present embodiment provides angular position information indicating the rotational angular position of motor 300 based on a rotation detection signal (resolver signal) corresponding to the rotational angle of motor 300. A data bus 3 connected to the RDC 2 for transmitting angular position information is provided. Further, the motor control device 100 is connected to the RDC 2, and based on the angular position information and the Z-phase pulse inputted via the signal line 4 for transmitting the Z-phase pulse, the data bus 3 and the signal line 4, the RDC 2 and the data bus 3, and an abnormality determination unit 52 that determines whether or not there is an abnormality in at least one of 3.

With this configuration, the signal transmission path is duplicated simply by adding one signal line 4, and the signal transmission path (data bus 3, board wiring pattern, package terminal, bonding wire, etc.) can be detected.

Therefore, in a vehicle equipped with a motor control device 100 having a general-purpose external RDC 2, not only can the above-mentioned safety goals be achieved, but also the general-purpose external RDC 2 can be used, so that the motor control device 100 can reduce the manufacturing cost of

Moreover, since it is only necessary to add one signal line 4 to the general-purpose external RDC 2, it is possible to provide the motor control device 100 having a robust structure and suppressing an increase in cost.

Further, the motor control device 100 according to the present embodiment includes a storage unit 53 that stores an error determination table 53a that associates the angular position detection error including the angular position detection error range with the number of revolutions of the motor 300. , the abnormality determination unit 52 determines whether there is an abnormality based on the angular position detection error range obtained by referring to the error determination table 53a and the angular position information when the rising edge of the Z-phase pulse is detected. can be configured to

With this configuration, simple failure diagnosis using the preset error determination table 53a is possible, and the processing load of the CPU constituting the processing unit 5 is reduced compared to the case of calculating the angular position detection error range in real time. is reduced. Therefore, an inexpensive CPU with low processing capability can be used, and the motor control device 100 with a robust structure can be provided while suppressing an increase in the manufacturing cost of the motor control device 100 .

Further, the abnormality determination unit 52 of the motor control device 100 according to the present embodiment compares the rotational angular position with the angular position detection error range after a certain period of time has elapsed since the rising edge of the Z-phase pulse was detected. It may be configured to determine that at least one of the RDC2 and the data bus is abnormal when the angular position exceeds the angular position detection error range.

Accurate failure diagnosis considering the angular position detection error range that fluctuates according to the number of rotations is possible, and even if the interrupt response time of the CPU constituting the processing unit 5 is long, the increase in the manufacturing cost of the motor control device 100 is reduced. It is possible to provide a motor control device 100 that is robust in structure while being restrained.

The configuration shown in the above embodiment shows an example of the content of the present invention, and it is possible to combine it with another known technology, and one configuration can be used without departing from the scope of the present invention. It is also possible to omit or change the part.

1: resolver 3: data bus 4: signal line 5: processing unit 5A: processing unit 6: gate drive circuit 7: inverter 21: angle detection unit 22: encoder 51: motor control unit 52: abnormality determination unit 53: storage unit 53a : Error determination table 53b: Detection error tolerance 100: Motor control device 100A: Motor control device 200: Battery 300: Motor

Claims (2)

a resolver digital converter that generates angular position information indicating the rotational angular position of the motor and a Z-phase pulse that is output once each time the motor rotates, based on a rotation detection signal corresponding to the rotational angle of the motor;
a data bus connected to the resolver-to-digital converter for transmitting the angular position information;
a signal line connected to the resolver digital converter and transmitting the Z-phase pulse;
an abnormality determination unit that determines whether or not there is an abnormality in at least one of the resolver digital converter and the data bus based on the angular position information and the Z-phase pulse input via the data bus and the signal line;
a storage unit that stores an error determination table that associates the angular position detection error including the angular position detection error range with the number of revolutions of the motor;
The abnormality determination unit determines the presence or absence of the abnormality based on the angular position detection error range obtained by referring to the error determination table and the rotational angular position when the rise of the Z-phase pulse is detected. Judging, motor controller. The abnormality determination section compares the rotational angular position with the angular position detection error range after a predetermined time has elapsed since the rise of the Z-phase pulse was detected, and determines that the rotational angular position is within the angular position detection error range. 2. The motor control device according to claim 1 , wherein it is determined that at least one of said resolver digital converter and said data bus has an abnormality when said value exceeds .

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