JP2015173516A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller capable of precisely controlling the motor torque free from changes in resistance value and temperature on a motor.SOLUTION: A target current calculation section 17 calculates a target current to be supplied to a motor M. When the motor M is in immobilized state and when the temperature on the motor M or an FET drive circuit 3 is smaller than a threshold value, the target current calculation section 17 increases the target current to increase the torque to thereby release the motor M from the immobilized state. When the motor M is in immobilized state and when the temperature on the motor M or FET drive circuit 3 is larger than a threshold value, the target current calculation section 17 reduces the target current to prevent heat generation on the motor M or the FET drive circuit 3.

Description

  The present invention relates to a motor control device that controls driving of a motor.

  Conventional motor control devices generate torque by controlling the voltage applied to the motor in order to release the fixed state of the motor (see, for example, Patent Document 1). The applied voltage is controlled by controlling the ON time (duty ratio) of the operating carrier cycle of the switching element connected between the power source and the motor.

JP 2008-115867 A

  However, the current supplied to the motor cannot be suppressed by controlling the applied voltage. Therefore, it is necessary to adjust the on-time of the operating carrier cycle of the switching element according to the resistance value of the motor for each motor so that it can be used within the rated allowable range of various components. Furthermore, since the resistance value of the motor also changes when the temperature around the motor and the motor coil alone changes, it is necessary to correct the on-time of the operation carrier cycle of the switching element according to the temperature change.

  Since the control device of Patent Document 1 controls the applied voltage even when observing the temperature of various components, the current supplied to the motor is indefinite. Therefore, the motor torque cannot be output with high accuracy. Moreover, in order to prevent the motor from generating excessive heat, the motor torque could not be output to the maximum.

  As described above, since the motor torque cannot be accurately output by controlling the applied voltage, there is a problem that the motor torque optimum for releasing the fixed state cannot be output.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a motor control device that accurately controls motor torque without being affected by the resistance value and temperature change of the motor. .

  A motor control device according to the present invention includes a drive circuit that supplies current to a motor by operating according to a target duty, a fixing determination unit that determines whether the motor is in a fixed state based on the rotational position of the motor, A temperature determination unit that determines whether the temperature of the drive circuit is equal to or lower than a threshold value, a target current supplied to the motor based on the current supplied to the motor by the drive circuit and the rotational position of the motor, and the motor is fixed Based on the target current calculated by the target current calculation unit that increases the target current when the temperature of the motor or the drive circuit is equal to or lower than the threshold and decreases the target current when the temperature is higher than the threshold. A target duty calculation unit that calculates the target duty and outputs the target duty to the drive circuit.

According to the present invention, since the current supplied to the motor is controlled, the motor torque can be accurately controlled without being influenced by the resistance value and temperature change of the motor. In addition, when the motor is in a fixed state and the temperature of the motor or drive circuit is lower than the threshold value, the target current is increased in order to escape from the fixed state. The motor torque can be increased and the motor torque can be output to the maximum.
Furthermore, when the motor is in a fixed state and the temperature of the motor or the drive circuit is higher than the threshold value, the target current is reduced, so that the heat generation of the motor or the drive circuit can be suppressed.

It is a block diagram which shows the structure of the motor control apparatus which concerns on Embodiment 1 of this invention. 3 is a flowchart illustrating an operation of the motor control device according to the first embodiment. It is a block diagram which shows the structure of the motor control apparatus which concerns on Embodiment 2 of this invention. It is a graph showing the relationship between the temperature of a FET drive circuit (or motor) and a target current.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration example of a motor control device 1 according to Embodiment 1 of the present invention. The motor control device 1 drives the motor M with electric power supplied from the power supply device 2, and includes a calculation unit 10 that controls a current supplied to the motor M and a current supplied to the motor M that is controlled by the calculation unit 10. An FET (field effect transistor) drive circuit 3 to be supplied, a current measurement circuit 4 that measures the current of the motor M and inputs it to the calculation unit 10, and a temperature that measures the temperature of the FET drive circuit 3 and inputs it to the calculation unit 10 It includes a measurement circuit 5 and a position detection circuit 6 that detects the rotational position of the motor M and inputs it to the calculation unit 10.

  The FET drive circuit 3 operates a plurality of bridge-connected FETs (not shown) based on the target duty input from the arithmetic unit 10 and supplies a current to the motor M. In the illustrated example, the FET drive circuit 3 is configured using an FET, but the type of the switching element is not limited.

  The current measurement circuit 4 measures the current supplied from the FET drive circuit 3 to the motor M and inputs it to the calculation unit 10. The installation location of the current measurement circuit 4 may be any location where the current supplied to the motor M can be measured.

The temperature measurement circuit 5 includes a temperature sensor and the like, measures the temperature of the FET drive circuit 3, and inputs the temperature to the calculation unit 10.
In the illustrated example, the temperature measurement circuit 5 measures the temperature of the FET drive circuit 3, but the measurement target is not limited to the FET drive circuit 3, and the temperature of the motor M may be measured.

The position detection circuit 6 detects the rotational position of the motor M and inputs angle information to the calculation unit 10.
The angle information here means an angle from the reference with respect to one point of 360 degrees at which the motor M rotates once.

  The calculation unit 10 is configured by a CPU (Central Processing Unit) (not shown), and when the CPU executes a program stored in an internal memory, the phase calculation unit 11, the position calculation unit 12, and the speed calculation unit 13. The functions as the target speed calculation unit 14, the temperature determination unit 15, the sticking determination unit 16, the target current calculation unit 17, and the target duty calculation unit 18 are realized.

The phase calculation unit 11 calculates the phase of the motor M (that is, the positional relationship between the coil and the magnet) based on the angle information input from the position detection circuit 6 and inputs the calculated phase to the target duty calculation unit 18.
The position calculation unit 12 calculates the position of the motor M (that is, the rotational position of the shaft) based on the angle information input from the position detection circuit 6, and the speed calculation unit 13, the target speed calculation unit 14, and the sticking determination Each is input to the unit 16.

The speed calculation unit 13 calculates the current rotation speed of the motor M based on the position of the motor M input from the position calculation unit 12, and inputs it to the target current calculation unit 17.
The target speed calculation unit 14 sets a target speed (hereinafter referred to as a target speed) based on the target position information input from the outside and the current position of the motor M input from the position calculation unit 12. Is calculated.

The temperature determination unit 15 determines whether the temperature measurement value input from the temperature measurement circuit 5 is equal to or lower than the temperature threshold value or greater than the temperature threshold value, and inputs the determination result to the target current calculation unit 17.
Here, the temperature threshold is an arbitrary temperature preset in the temperature determination unit 15. In this example, since the temperature measurement circuit 5 measures the temperature of the FET drive circuit 3, the guaranteed temperature of the parts of the FET drive circuit 3 is set as the temperature threshold. When the temperature measurement circuit 5 measures the temperature of the motor M, the upper limit temperature of the operating temperature range of the motor M may be set as the temperature threshold value.

The sticking determination unit 16 compares the target position information input from the outside with the current position of the motor M input from the position calculation unit 12, and calculates a position deviation. The sticking determination unit 16 determines that the motor M is operating normally if the calculated position deviation is smaller than the deviation threshold, and determines that the motor M is stuck if the calculated position deviation is greater than or equal to the deviation threshold. The result is input to the target current calculation unit 17.
Here, the deviation threshold is a position deviation value that is regarded as a state in which the motor M is fixed, and is set in advance in the fixing determination unit 16.

The target current calculation unit 17 compares the target speed input from the target speed calculation unit 14 with the current speed of the motor M input from the speed calculation unit 13 and compares the target value of the current supplied to the motor M ( Hereinafter, the target current is calculated. Since the method for calculating the target current from the speed may use a known technique, a detailed description thereof will be omitted.
Further, the target current calculation unit 17 adjusts the calculated target current based on the determination results respectively input from the temperature determination unit 15 and the sticking determination unit 16, and the adjusted target current is supplied to the target duty calculation unit 18. input. A method for adjusting the target current will be described later.

  The target duty calculation unit 18 is based on the target current input from the target current calculation unit 17 and the phase of the motor M input from the phase calculation unit 11. Phase target voltage) is calculated and input to the FET drive circuit 3.

Next, the operation of the motor control device 1, particularly the method for adjusting the target current will be described with reference to the flowchart of FIG.
In step ST1, the target current calculation unit 17 calculates a target current. That is, the phase calculator 11 calculates the phase of the motor M, the position calculator 12 calculates the position of the motor M from the phase, and the target speed calculator 14 calculates the target speed from the position of the motor M and the target position information. The target current calculation unit 17 calculates the target current from the target speed and the current speed.
In step ST2, the target duty calculation unit 18 calculates the target duty from the target current, and the FET drive circuit 3 operates according to the target duty to supply current to the motor M.

  In step ST3, the sticking determination unit 16 confirms whether the deviation between the target position and the actual position of the motor M converges to a value less than the deviation threshold. If the position deviation is smaller than the deviation threshold value (step ST3 “NO”), the sticking determination unit 16 determines that the motor M is operating normally, and the motor control device 1 repeats the processes of steps ST1 to ST3.

  On the other hand, if the position deviation does not converge to a value less than the deviation threshold even after the predetermined time has elapsed or does not change from a value greater than or equal to the deviation threshold, and the position deviation remains greater than the deviation threshold (step ST3 “YES”), The sticking determination unit 16 determines that the motor M is in a sticking state, and inputs the determination result to the target current calculation unit 17. In subsequent step ST4, the temperature determination unit 15 compares the temperature measurement value with the temperature threshold value. When the measured temperature value is smaller than the temperature threshold value (step ST4 “YES”), the temperature determination unit 15 determines that the FET drive circuit 3 does not generate abnormal heat, and inputs the determination result to the target current calculation unit 17.

  When the motor M is in the fixed state and the FET drive circuit 3 is not abnormally heated, the target current calculation unit 17 increases the target current continuously or stepwise in order to cause the motor M to escape from the fixed state. The torque is gradually increased by making adjustments. Specifically, the target current calculation unit 17 increases the target current by one step (step ST5), the target duty calculation unit 18 calculates the target duty from the adjusted target current, and the FET drive circuit 3 sets the target duty to the target duty. A current based on this is supplied to the motor M (step ST6). Subsequently, the sticking determination unit 16 determines whether or not the sticking state is established based on the adjusted position of the motor M (step ST7). When the fixed state continues (step ST7 “YES”), after the temperature determination unit 15 determines the temperature (step ST4 “YES”), the target current calculation unit 17 further increases the adjusted target current by one step. (Step ST5), the torque is increased. By repeating the processes of steps ST4 to ST7, the torque of the motor M gradually increases, and it is possible to escape from the fixed state on the way. When the fixed state is escaped, the positional deviation becomes smaller than the deviation threshold value (step ST7 “NO”), and the routine returns to the normal control of steps ST1 to ST3. Therefore, it is possible to minimize the torque required to escape from the fixed state.

  In the above description, the target current calculation unit 17 is adjusted so that the target current increases continuously or stepwise. However, the target current calculation unit 17 is not limited to this. The target current may be increased to such an extent that it does not cause it.

  On the other hand, when the measured temperature value is equal to or higher than the temperature threshold value (step ST4 “NO”), in order to protect the FET drive circuit 3 from heat, the torque of the motor M is reduced to reduce the heat generation amount. Specifically, the target current calculation unit 17 decreases the target current (step ST8), the target duty calculation unit 18 calculates the target duty from the adjusted target current, and the FET drive circuit 3 uses the current based on the target duty. Is supplied to the motor M (step ST9). In step ST8, the motor M may be stopped by setting the target current to 0A. By this adjustment, the heat generation amount of the FET drive circuit 3 is reduced.

  In the control of step ST9, since the torque of the motor M is smaller than that in the normal control of step ST2, it is difficult to escape from the fixed state. Therefore, for example, after the time until the FET drive circuit 3 cools, the arithmetic unit 10 resets the motor control device 1 and starts the process again from step ST1, whereby the motor M can escape from the fixed state.

As described above, according to the first embodiment, the motor control device 1 is in the state where the motor M is fixed based on the FET drive circuit 3 that supplies current to the motor M by operating according to the target duty and the rotational position of the motor M. A determination unit 16 for determining whether or not the temperature of the motor M or the FET drive circuit 3 is equal to or lower than a threshold value, a current supplied to the motor M by the FET drive circuit 3 and the motor M The target current supplied to the motor M is calculated based on the rotation position of the motor M. When the motor M is in a fixed state, the target current is increased when the temperature of the motor M or the FET drive circuit 3 is equal to or lower than the threshold, A target current calculation unit 17 that reduces the target current when larger than the target current, and calculates a target duty based on the target current calculated by the target current calculation unit 17 and outputs the target duty to the FET drive circuit 3 That was configured to include a target Duty calculator 18.
Thus, since the motor control apparatus 1 controls the current supplied to the motor M, the motor torque can be accurately controlled without being affected by the resistance value and temperature change of the motor M.
In addition, when the motor M is in the fixed state and the temperature of the motor M or the FET drive circuit 3 is equal to or lower than the threshold value, the target current is increased in order to escape from the fixed state. It is possible to increase the current up to the limit temperature, and to output the maximum torque. Further, when the motor M is in the fixed state and the temperature of the motor M or the FET drive circuit 3 is higher than the threshold value, the target current is reduced, so that the heat generation of the motor M or the FET drive circuit 3 can be suppressed. it can.

  According to the first embodiment, the motor control device 1 includes the temperature measurement circuit 5, and the temperature measurement circuit 5 is configured to measure the temperature of the motor M or the FET drive circuit 3. Thus, since the temperature measurement circuit 5 directly measures the temperature of the motor M or the FET drive circuit 3, an accurate temperature can be easily obtained. Also, components can be protected from heat based on accurate temperature.

  Further, according to the first embodiment, the target current calculation unit 17 supplies the motor M from the FET drive circuit 3 when the motor M is in the fixed state and the temperature of the motor M or the FET drive circuit 3 is equal to or lower than the threshold value. The target current calculated based on the current and the rotational position of the motor M is configured to increase continuously or stepwise. For this reason, the torque of the motor M can be gradually increased to escape from the fixed state. Moreover, the torque required for escape can be minimized.

Embodiment 2. FIG.
In the first embodiment, the temperature of the FET drive circuit 3 or the motor M is measured using the temperature measurement circuit 5, but is estimated in the second embodiment.

  FIG. 3 is a block diagram illustrating a configuration of the motor control device 1 according to the second embodiment. The motor control device 1 of FIG. 3 includes a temperature estimation unit 20 instead of the temperature measurement circuit 5. Further, the motor control device 1 of FIG. 3 newly includes a current estimation unit 21. Since the other configuration is the same as that of FIG. 1, the same reference numerals are given and the description thereof is omitted.

  FIG. 4 is an example of a graph showing the relationship between the temperature of the FET drive circuit 3 (or the motor M) and the target current. The vertical axis represents temperature, and the horizontal axis represents the energization time of the target current. The temperature of the FET drive circuit 3 (or the motor M) becomes higher as the target current is larger and the energization time of the target current is longer.

  The temperature estimation unit 20 estimates the temperature of the FET drive circuit 3 (or the motor M) corresponding to the target current calculated by the target current calculation unit 17 based on the relationship between the temperature and the target current in the graph shown in FIG. And it inputs into the temperature determination part 15 as a temperature estimated value. The temperature determination unit 15 compares the estimated temperature value input from the temperature estimation unit 20 with the temperature threshold value, and determines abnormal heat generation of the FET drive circuit 3 (or the motor M).

The temperature estimation method is not limited to the above method.
For example, the temperature estimation unit 20 calculates the temperature of the FET drive circuit 3 (or motor M) based on the voltage applied to the FET of the FET drive circuit 3 (or the voltage applied to the motor M by the FET drive circuit 3). presume. Since the FET drive circuit 3 has a known resistance value (or resistance value of the motor M), the temperature estimation unit 20 obtains a current from the resistance value and the applied voltage, and shows the temperature corresponding to the obtained current in the graph of FIG. Estimated from

  Further, for example, the temperature estimation unit 20 estimates the temperature of the FET drive circuit 3 (or the motor M) based on the target duty at which the FET drive circuit 3 operates. Since the power supply voltage of the power supply device 2 is known, the temperature estimation unit 20 obtains an applied voltage from the power supply voltage and the target duty, obtains a current from the obtained applied voltage and a known resistance value, and calculates a temperature corresponding to the obtained current. It is estimated from the graph of FIG.

For example, the temperature estimation unit 20 may use a graph representing the relationship between temperature and power consumption instead of the graph of FIG. 4 representing the relationship between temperature and current.
The temperature estimation unit 20 may estimate the temperature using data obtained by tabulating the graph, or may calculate the temperature by calculating a function obtained by formulating the graph.

  In the first embodiment, the current measurement circuit 4 measures the current of each of the three phases. However, in the second embodiment, the current measurement circuit 4 measures the current of any one of the three phases and estimates the current. The unit 21 estimates the remaining two-phase current using the one-phase current measurement value.

  As described above, according to the second embodiment, the motor control device 1 includes the temperature estimation unit 20, and the temperature estimation unit 20 includes the target duty, the voltage applied to the motor M or the FET drive circuit 3, and the motor M or FET. The temperature of the motor M or the FET drive circuit 3 is estimated based on at least one of the currents flowing through the drive circuit 3. For this reason, it is not necessary to install the temperature measurement circuit 5 (shown in FIG. 1), and the space can be secured and the price can be reduced accordingly.

  In the present invention, within the scope of the invention, any combination of each embodiment, any component of each embodiment can be modified, or any component can be omitted in each embodiment. .

  DESCRIPTION OF SYMBOLS 1 Motor control apparatus, 2 Power supply device, 3 FET drive circuit, 4 Current measurement circuit, 5 Temperature measurement circuit, 6 Position detection circuit, 10 Calculation part, 11 Phase calculation part, 12 Position calculation part, 13 Speed calculation part, 14 Target Speed calculation unit, 15 temperature determination unit, 16 sticking determination unit, 17 target current calculation unit, 18 target duty calculation unit, 20 temperature estimation unit, 21 current estimation unit, M motor.

Claims (4)

A drive circuit for supplying current to the motor by operating in accordance with the target duty;
A fixing determination unit that determines whether or not the motor is in a fixed state based on a rotational position of the motor;
A temperature determination unit for determining whether the temperature of the motor or the drive circuit is equal to or lower than a threshold;
The target current supplied to the motor is calculated based on the current supplied to the motor by the drive circuit and the rotational position of the motor. When the motor is in a fixed state, the temperature of the motor or the drive circuit is equal to or less than the threshold value. A target current calculation unit that increases the target current at the time, and decreases the target current when the temperature is higher than the threshold;
A motor control device comprising: a target duty calculation unit that calculates the target duty based on the target current calculated by the target current calculation unit and outputs the target duty to the drive circuit.   The motor control device according to claim 1, further comprising a temperature measurement circuit that measures a temperature of the motor or the drive circuit.   A temperature estimation unit that estimates the temperature of the motor or the drive circuit based on at least one of the target duty, a voltage applied to the motor or the drive circuit, and a current flowing through the motor or the drive circuit. The motor control device according to claim 1, further comprising:   The target current calculation unit calculates a current supplied from the drive circuit to the motor and a rotational position of the motor when the motor is in a fixed state and the temperature of the motor or the drive circuit is equal to or lower than the threshold 4. The motor control device according to claim 1, wherein the target current is increased continuously or stepwise.

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