JP5724353B2 - Brushless motor control device for electric pump - Google Patents

Description

  The present invention relates to a control device for a brushless motor for an electric pump.

  Conventionally, in a vehicle having a so-called idle stop function for automatically stopping an engine when temporarily stopped, the supply of hydraulic pressure to a transmission or the like is ensured even during an idle stop by using an electric pump. As a drive source of such an electric pump, a brushless motor is generally used. However, since the electric pump is disposed in a high temperature environment such as an engine room, a sensorless type is considered in consideration of heat resistance of a rotation sensor such as a hall element. Is widely used (see, for example, Patent Document 1).

  In many cases, this type of brushless motor employs a 120-degree energization method in which a motor coil is energized only in a 120-degree section of an electrical angle of 180 degrees, and an induced voltage (back electromotive force) generated in each motor coil when the motor is driven. The rotational position of the rotor is detected based on (electric power).

  However, since no induced voltage is generated when the rotor is stopped, the rotational position of the rotor cannot be detected when the brushless motor is started. Therefore, conventionally, a brushless motor is started by forcibly rotating the rotor by switching a plurality of energization patterns to each motor coil in a predetermined order (forced commutation) regardless of the rotational position of the rotor. doing. Then, when the rotational speed of the rotor increases and the rotational position can be stably detected based on the induced voltage generated in the motor coil, driving (sensorless driving) is performed according to the rotational position of the rotor. .

JP 2006-280088 A Japanese Patent No. 4056750

  By the way, since the viscosity of the hydraulic oil supplied to the transmission or the like by the electric pump changes greatly according to the oil temperature, the load of the brushless motor greatly changes according to the oil temperature. However, in the conventional configuration, at the time of starting the brushless motor (at the time of forced commutation), no consideration is given to the fluctuation of the load due to the change of the oil temperature, which may cause an increase in current consumption or a step-out. .

  Specifically, when the oil temperature is high, the viscosity of the hydraulic oil becomes low and the rotor is likely to rotate. Therefore, even if the rotation position of the rotor becomes the rotation position to be switched to the next energization pattern, it does not switch. There is a risk of reducing the rotational speed of the rotor. As a result, the time required to increase the rotational speed of the rotor is lengthened, resulting in an increase in current consumption. On the other hand, if the oil temperature is low, the viscosity of the hydraulic oil becomes high and the rotor is difficult to rotate.Therefore, the energization pattern is changed before the rotation position of the rotor is changed to the next energization pattern. Step out by switching.

  Patent Document 2 discloses an activation method in which the switching cycle of the energization pattern is changed according to the state of the brushless motor at the time of activation. However, in the configuration of Patent Document 2, since the switching cycle is changed according to the state of the brushless motor itself, a torque sensor is required to change the switching cycle according to the load of the motor. This leads to an increase in the size of the brushless motor (electric pump). Therefore, it is not preferable to apply such a configuration from the viewpoint of downsizing the brushless motor, and there is still room for improvement.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a brushless motor control device for an electric pump capable of suppressing an increase in current consumption and a step-out during startup. There is.

  In order to achieve the above-mentioned object, the invention described in claim 1 includes a drive circuit for energizing three-phase drive power to a motor coil of a brushless motor that drives an electric pump, and a plurality of energization patterns for the motor coil in advance. A control device for a brushless motor for an electric pump, comprising a starting means for starting the brushless motor by forcibly rotating a rotor by switching in a predetermined order, the hydraulic oil supplied by the electric pump The gist is provided with an oil temperature detecting means for detecting temperature, and the starting means speeds up the switching cycle of the energization pattern as the oil temperature becomes higher.

  According to the above-described configuration, the starter speeds up the cycle of switching the energization pattern as the oil temperature of the hydraulic oil becomes higher. Even if it becomes the rotation position which should be switched, it can suppress that it will be in the state which does not switch. As a result, the rotational speed of the rotor can be quickly increased, and an increase in current consumption can be suppressed. On the other hand, the starting means slows down the switching period of the energization pattern as the oil temperature of the hydraulic oil becomes lower. Therefore, when the oil temperature is low, before the rotational position of the rotor becomes the rotational position to be switched to the next energization pattern. It is possible to prevent the energization pattern from being switched and to suppress the step-out. And in the said structure, in order to change a switching period based on the oil temperature of the hydraulic oil which has a correlation with the load of a brushless motor, it is not necessary to provide a torque sensor, and the enlargement of a brushless motor (electric pump) is suppressed. Can do.

Further, in the invention described in claim 1, before Symbol brushless motor, there is the motor output is controlled through changes of the duty ratio of the switching elements constituting the driving circuit, said activation means, the oil temperature The higher the value, the higher the duty ratio .

  Normally, the motor output at the time of forced commutation (the amount of current applied to the motor coil) is smaller than the motor output after startup, so the motor output quickly follows the target value after the brushless motor starts. From such a viewpoint, it is desirable to increase the duty ratio of the switching element during forced commutation. On the other hand, from the viewpoint of suppressing an increase in current consumption, it is desirable to reduce the duty ratio.

  In this regard, according to the above-described configuration, when the oil temperature is high and the increase in current consumption can be suppressed, the duty ratio is increased to suppress the increase in current consumption and follow up after the brushless motor is started. Can be improved. On the other hand, when the oil temperature is low and there is a possibility that the current consumption will increase significantly due to the rotor stepping out and stopping, the increase in the current consumption can be reliably suppressed by reducing the duty ratio. .

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the brushless motor for electric pumps which can suppress the increase in consumption current or a step-out at the time of starting can be provided.

The block diagram which shows the electric constitution of an electric pump. The schematic diagram which shows the electricity supply pattern to a motor coil. The block diagram which shows the electrical constitution of a rotation position signal generation part. The wave form diagram of the terminal voltage and rotation position signal of a motor coil. The flowchart which shows the process sequence at the time of starting of a brushless motor. (A) The schematic block diagram of the map used for the calculation of a switching period, (b) The schematic block diagram of the map used for the calculation of a duty ratio.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
An electric pump 1 shown in FIG. 1 is mounted on a vehicle having a so-called idle stop function that automatically stops an engine when temporarily stopped, and supplies hydraulic pressure to a transmission or the like. As shown in FIG. 1, the electric pump 1 includes a brushless motor 3 that drives the pump main body 2 and an ECU 4 as a control device that controls the operation of the brushless motor 3.

  The brushless motor 3 employs a sensorless type that is not provided with a rotation sensor that detects the rotational position of the rotor 11, and the ECU 4 operates the three-phase motor coils 12 u, 12 v, The rotational position (rotation angle) of the rotor 11 is detected based on the induced voltage (back electromotive force) generated at 12w. The ECU 4 is configured to supply three-phase driving power to the brushless motor 3 by energizing the motor coils 12u, 12v, and 12w of each phase with a 120-degree rectangular wave.

  More specifically, the ECU 4 switches the energization pattern, which is a combination of voltages applied to the motor coils 12u, 12v, 12w, and supplies three-phase driving power, and outputs a motor control signal to the driving circuit 21. And a microcomputer 22 for driving the brushless motor 3.

  The drive circuit 21 is formed by connecting a plurality of FETs (field effect transistors) 23a to 23f as switching elements. Specifically, the drive circuit 21 is formed by connecting in parallel a series circuit of each set of FETs 23a and 23d, FETs 23b and 23e, and FETs 23c and 23f. The points 24u, 24v, 24w are connected to the motor coils 12u, 12v, 12w of each phase of the brushless motor 3, respectively.

  That is, the drive circuit 21 is configured as a known PWM inverter in which a pair of switching elements connected in series is a basic unit (switching arm) and three switching arms corresponding to each phase are connected in parallel. . The motor control signal output from the microcomputer 22 is a gate on / off signal that defines the switching states of the FETs 23a to 23f constituting the drive circuit 21.

  Then, in response to the motor control signals applied to the respective gate terminals, the FETs 23a to 23f are turned on / off, and the energization patterns to the motor coils 12u, 12v, 12w of the respective phases are switched. ) 25 DC voltage is converted into three-phase (U, V, W) driving power and output to the brushless motor 3. In this embodiment, since 120-degree rectangular wave energization is performed, there are six energization patterns to the motor coils 12u, 12v, and 12w as shown in FIG. 2, and the energization patterns (1) to (6) are in this order. By switching at, the brushless motor 3 is driven. In FIG. 2, the direction of current flow is schematically indicated by a thick arrow.

  As shown in FIG. 1, voltage sensors 26u, 26v, 26w for detecting terminal voltages Vu, Vv, Vw of the motor coils 12u, 12v, 12w are connected to the microcomputer 22. The microcomputer 22 is driven based on the rotational position signals S1 to S3 and the rotational position signal generator 27 that generates rotational position signals S1 to S3 indicating the rotational position of the rotor 11 based on the terminal voltages Vu, Vv, and Vw. And a motor control signal generation unit for generating a motor control signal to be output to the circuit.

  As shown in FIG. 3, the rotational position signal generation unit 27 includes a voltage dividing circuit 31 formed by connecting two resistors R1 and R2 having the same resistance value in series, and a reference voltage V0 output from the voltage dividing circuit 31 (this In the embodiment, three comparators 32u, 32v, and 32w that respectively compare the terminal voltage Vu, Vv, and Vw with a voltage half that of the in-vehicle power supply 25) are provided. Each of the comparators 32u, 32v, and 32w outputs rotational position signals S1 to S3 based on a comparison between the terminal voltages Vu, Vv, and Vw and the reference voltage V0. Specifically, each of the comparators 32u, 32v, and 32w outputs “1 (high level)” as the rotation position signals S1 to S3 when the terminal voltages Vu, Vv, and Vw are larger than the reference voltage V0. When the terminal voltages Vu, Vv, and Vw are equal to or lower than the reference voltage V0, “0 (low level)” is output as the rotation position signals S1 to S3. The motor control signal generation unit 28 generates a motor control signal based on the rotation position signals S1 to S3 so that the energization pattern to the motor coils 12u, 12v, and 12w is switched according to the rotation position of the rotor 11.

  Here, as shown in FIG. 4, the terminal voltages Vu, Vv, and Vw are different in phase by 120 degrees, and the power supply voltage is detected in the energized section of 120 degrees energized among the electrical angles of 180 degrees. In the 60-degree pause section in which the energization is paused, the induced voltage generated in each motor coil 12u, 12v, 12w is detected. When the FETs 23a to 23f are switched from on to off, noise is generated due to parasitic diodes (not shown) of the FETs 23a to 23f. The rotational position signals S1 to S3 change at the time (zero cross point) when the terminal voltages Vu, Vv, and Vw become the reference voltage V0, and according to the rotational position of the rotor 11 by removing the noise (101). ) → (100) → (110) → (010) → (011) → (001). Thereby, the motor control signal generation unit 28 can generate a motor control signal for switching the energization pattern to the motor coils 12u, 12v, 12w according to the rotational position of the rotor 11 based on the rotational position signals S1 to S3. Yes.

  Further, as shown in FIG. 1, the microcomputer 22 controls the amount of current supplied to the motor coils 12u, 12v, 12w through the change of the duty ratio, which is the ratio of the on-time of each of the FETs 23a to 23f, so that the brushless motor 3 Output (motor torque) is controlled.

  Specifically, the microcomputer 22 is connected to a current sensor 41 for detecting an actual current value I supplied to the brushless motor 3 and a host ECU for controlling the operation of the transmission. The motor control signal generator 28 receives the current command value I * output from the host ECU and the actual current value I detected by the current sensor 41 in addition to the rotational position signals S1 to S3. The motor control signal generator 28 performs a feedback control to cause the actual current value I to follow the current command value I *, thereby performing a pulse with a duty ratio corresponding to the deviation between the current command value I * and the actual current value I. A width-modulated motor control signal is generated. The host ECU calculates the current command value I * based on the hydraulic pressure supplied from the electric pump, the engine speed, and the like. The microcomputer 22 drives the brushless motor 3 by outputting the motor control signal generated as described above to the drive circuit 21.

Next, activation of the brushless motor by the ECU of this embodiment will be described.
Since no induced voltage is generated when the brushless motor 3 is stopped, the microcomputer 22 forcibly turns the rotor 11 by switching the energization pattern in a predetermined order (forced commutation) regardless of the rotational position of the rotor 11. The brushless motor 3 is started by rotating. Then, the rotational speed of the rotor 11 is increased, and the induced voltage generated in each motor coil 12u, 12v, 12w is stabilized, so that the combination of the rotational position signals S1 to S3 is regularly performed in the order described above for a predetermined time. When changed, the brushless motor 3 is driven (sensorless drive) based on the rotational position signals S1 to S3 and the current command value I *. The motor control signal generator 28 is provided with a memory 42 and a timer 43 that store the order in which the rotational position signals S1 to S3 change regularly. That is, in the present embodiment, the microcomputer 22 corresponds to the activation unit.

  Here, as described above, in the brushless motor 3 for the electric pump, the load greatly varies depending on the oil temperature θ of the hydraulic oil. Therefore, when the oil pattern θ is high and low, the energization pattern switching period T is the same. There is a risk that current consumption will increase or step out.

  In consideration of this point, as shown in FIG. 1, the microcomputer 22 is connected to an oil temperature sensor 51 as an oil temperature detecting means for detecting the oil temperature θ of the hydraulic oil. The oil temperature θ of the hydraulic oil is input. The motor control signal generator 28 changes the energization pattern switching period T in accordance with the oil temperature θ.

  Specifically, the motor control signal generator 28 generates a motor control signal whose switching cycle T becomes the first switching cycle T1 when the oil temperature θ is larger than a preset threshold value θth at the time of startup. Generate. On the other hand, when the oil temperature θ is equal to or lower than the threshold θth, the motor control signal generation unit 28 generates a motor control signal in which the switching cycle T becomes the second switching cycle T2 that is slower than the first switching cycle T1. Thus, the higher the oil temperature θ, the faster the switching cycle T is.

  In addition, the motor control signal generation unit 28 generates a motor control signal in which the duty ratio D of the FETs 23a to 23f becomes the first duty ratio D1 when the oil temperature θ is larger than the threshold value θth at the time of startup. . On the other hand, when the oil temperature θ is equal to or lower than a preset threshold value θth, the motor control signal generation unit 28 has a motor control signal that causes the duty ratio D to be a second duty ratio D2 that is lower than the first duty ratio D1. Is generated. Thereby, the higher the oil temperature θ, the higher the duty ratio D is.

Next, a processing procedure when the brushless motor is activated by the ECU (microcomputer) according to the present embodiment will be described with reference to the flowchart of FIG.
When the microcomputer 22 acquires the rotational position signals S1 to S3 and the oil temperature θ as sensor values (step 101), the rotational position signals S1 to S3 regularly change for a predetermined time and detects the rotational position of the rotor 11. It is determined whether or not it is possible (step 102). Subsequently, when the rotational position of the rotor 11 cannot be detected (step 102: NO), it is determined whether or not the oil temperature θ is larger than the threshold value θth (step 103). When the oil temperature θ is larger than the threshold value θth (step 103: YES), a motor control signal for setting the switching period T to the first switching period T1 and the duty ratio D to the first duty ratio D1 is generated. (Step 104) and forced commutation is performed (Step 105).

  On the other hand, when the oil temperature θ is equal to or lower than the threshold θth (step 103: NO), the motor control signal that sets the switching cycle T to the second switching cycle T2 and sets the duty ratio D to the second duty ratio D2. Is generated (step 106), and forced commutation is performed (step 105). Then, when the rotational speed of the rotor 11 increases, the rotational position signals S1 to S3 change regularly for a predetermined time, and the rotational position of the rotor 11 can be detected (step 101: YES). The routine proceeds to normal control for generating a motor control signal based on the rotational position signals S1 to S3 and the current command value I * (step 107).

As described above, according to the present embodiment, the following operational effects can be achieved.
(1) The ECU 4 includes an oil temperature sensor 51 that detects the oil temperature θ of the hydraulic oil supplied by the electric pump 1. The microcomputer 22 sets the energization pattern switching cycle T as the first switching cycle T1 when the oil temperature θ is larger than the threshold θth, and sets the switching cycle T when the oil temperature θ is equal to or lower than the threshold θth. The second switching cycle T2 is slower than the first switching cycle T1.

  According to the above configuration, when the hydraulic oil temperature θ is greater than the threshold value θth, the energization pattern switching period T is accelerated. Therefore, when the hydraulic oil temperature θ is high, the rotational position of the rotor 11 is the next. Even if it becomes the rotation position which should be switched to this electricity supply pattern, it can suppress that it will be in the state which does not switch. As a result, the rotational speed of the rotor 11 can be quickly increased, and an increase in current consumption can be suppressed. On the other hand, when the oil temperature θ of the hydraulic oil is equal to or less than the threshold value θth, the energization pattern switching period T is delayed. It is possible to prevent the energization pattern from being switched before becoming, and to suppress step-out. In the above configuration, since the switching cycle T is changed based on the hydraulic oil temperature θ correlated with the load of the brushless motor 3, only the oil temperature sensor 51 is provided and the torque sensor is not provided. 3 (electric pump 1) can be prevented from increasing in size. Further, since the motor control signal generation unit 28 changes the switching cycle T by comparing the oil temperature θ with the threshold value θth, it is possible to suppress an increase in the calculation load.

  (2) The motor control signal generator 28 sets the duty ratio D to the first duty ratio D1 when the oil temperature θ is greater than the threshold θth, and the duty ratio when the oil temperature θ is equal to or less than the threshold θth. D is a second duty ratio D2 that is lower than the first duty ratio D1.

  Normally, the motor output at the time of forced commutation (the amount of current applied to the motor coils 12u, 12v, 12w) is smaller than the motor output after startup, so that the motor output is quickly increased after the brushless motor 3 is started. From the viewpoint of causing the target value to follow the target value, it is desirable to increase the duty ratio D during forced commutation. On the other hand, it is desirable to reduce the duty ratio D from the viewpoint of suppressing an increase in current consumption. In this regard, according to the above configuration, the brushless motor 3 is activated while suppressing the increase in current consumption by increasing the duty ratio D when the oil temperature θ is high and the increase in current consumption can be suppressed. The following ability can be improved. On the other hand, when the oil temperature θ is low and there is a possibility that the current consumption may increase significantly due to the rotor 11 stepping out and stopping, the increase in the current consumption is reliably suppressed by reducing the duty ratio D. be able to. Moreover, since the motor control signal generation unit 28 changes the duty ratio D by comparing the oil temperature θ and the threshold value θth, it is possible to suppress an increase in the calculation load.

In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.
In the above embodiment, the energization pattern switching period T is changed based on the comparison between the oil temperature θ and the threshold value θth. However, the present invention is not limited to this. For example, the oil temperature θ and the switching period shown in FIG. A map showing the relationship with T may be provided in the motor control signal generator 28, and the switching cycle T corresponding to the oil temperature θ may be calculated by referring to the map. Further, for example, a map showing the relationship between the oil temperature θ and the duty ratio D as shown in FIG. 6B is provided in the motor control signal generator 28, and the duty corresponding to the oil temperature θ is obtained by referring to the map. The ratio D may be calculated. In this configuration, the energization pattern switching period T and the duty ratio D can be calculated with high accuracy in accordance with the oil temperature θ of the hydraulic oil, that is, the load of the brushless motor 3, thereby effectively increasing the current consumption and stepping out. Can be suppressed.

  In the above embodiment, the motor control signal generation unit 28 increases the duty ratio D as the oil temperature θ increases. However, the present invention is not limited thereto, and the duty ratio D increases as the oil temperature θ decreases. May be. For example, when the oil temperature θ is larger than the threshold θth, the duty ratio D is set to the second duty ratio D2, and when the oil temperature θ is equal to or lower than the threshold θth, the duty ratio D is set to the first duty ratio D1. Can do.

In the above embodiment, the duty ratio D is changed according to the oil temperature θ. However, the present invention is not limited to this, and the duty ratio D may be constant regardless of the oil temperature θ.
In the above embodiment, the oil temperature θ of the hydraulic oil is directly detected by the oil temperature sensor 51. However, the present invention is not limited to this. The temperature θ may be estimated.

  In the above embodiment, it is determined that the rotational position of the rotor 11 can be detected when the combination of the rotational position signals S1 to S3 changes regularly in a predetermined order, and the process proceeds to normal control. I did it. However, the present invention is not limited to this. For example, when the rotational speed of the rotor is detected from the interval between the zero cross points, and the rotational speed exceeds the predetermined rotational speed, the rotational position of the rotor 11 can be detected. You may make it transfer.

In the above embodiment, the present invention is embodied in an electric pump that supplies hydraulic pressure to a vehicle transmission. However, the present invention may be embodied in an electric pump used for other applications.
Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.

(B) In the control device for a brushless motor for the electric pump, the activation means, comparing the oil temperature with the threshold value, if the oil temperature is greater than the threshold value, first switches the switching period And when the oil temperature is equal to or lower than the threshold, the switching cycle is set to a second switching cycle that is slower than the first switching cycle and the duty cycle A control device for a brushless motor for an electric pump, wherein the ratio is a second duty ratio lower than the first duty ratio. According to the said structure, it can suppress that the calculation load of a starting means increases.

(B) In the control device for a brushless motor for the electric pump, the activation means includes a map showing the relationship between the oil temperature and the switching period or the duty ratio, the switching period or the on the basis of the map A control device for a brushless motor for an electric pump, characterized by calculating a duty ratio. According to the above configuration, the switching cycle and the duty ratio can be calculated with high accuracy according to the oil temperature of the hydraulic oil, that is, the load of the brushless motor, and the increase in current consumption and the step-out can be effectively suppressed. it can.

  (C) In a brushless motor control method for an electric pump that starts a brushless motor by forcibly rotating a rotor by switching an energization pattern to a motor coil of a brushless motor that drives an electric pump in a predetermined order. The method for controlling a brushless motor for an electric pump, characterized in that the switching cycle of the energization pattern is made earlier as the temperature of hydraulic oil supplied by the electric pump becomes higher. According to the said structure, the effect similar to Claim 1 can be acquired.

  DESCRIPTION OF SYMBOLS 1 ... Electric pump, 2 ... Pump main body, 3 ... Brushless motor, 4 ... ECU, 11 ... Rotor, 12u, 12v, 12w ... Motor coil, 21 ... Drive circuit, 22 ... Microcomputer, 23a-23f ... FET, 26u, 26v , 26w ... voltage sensor, 27 ... rotational position signal generation unit, 28 ... motor control signal generation unit, 51 ... oil temperature sensor, D ... duty ratio, D1 ... first duty ratio, D2 ... second duty ratio, S1 S3: Rotational position signal, T: Switching period, T1: First switching period, T2: Second switching period, θ: Oil temperature, θth: Threshold value.

Claims (1)

The rotor is forcibly rotated by switching a drive circuit that supplies three-phase drive power to a motor coil of a brushless motor that drives an electric pump and a plurality of energization patterns to the motor coil in a predetermined order. A control device for a brushless motor for an electric pump, comprising a starting means for starting the brushless motor,
An oil temperature detecting means for detecting the oil temperature of the hydraulic oil supplied by the electric pump;
The brushless motor is one in which the motor output is controlled through a change in the duty ratio of the switching elements constituting the drive circuit.
The starter makes the switching cycle of the energization pattern faster as the oil temperature becomes higher, and increases the duty ratio as the oil temperature becomes higher .

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