Motor control device

Abstract

To provide a motor control device capable of stabilizing motor operation during low-speed periods.SOLUTION: An ECU calculates an output duty ratio using proportional and integral terms according to a deviation between a command speed to a motor and an actual speed of the motor and controls the motor (S18, S19) by driving an inverter circuit with the calculated output duty ratio. The ECU then sets a deviation magnification by which proportional and integral terms are multiplied (S16a, S17a). At this time, the ECU sets the deviation multiplier A to be a higher output duty ratio when a rise speed is slower than when a rise speed is faster according to an actual speed of rise in RPM when it is determined that the period is a low-speed period.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a motor control device. [Background technology]

[0002] One example of a conventional motor control device is a brushless motor control device disclosed in Patent Document 1. When the rotation speed of the rotor is below a predetermined rotation speed, the brushless motor control device performs rotation control using regular energization timing generated by regular timing generation means, and when the rotation speed of the rotor reaches or exceeds the predetermined rotation speed, switches to rotation control using advance-angle energization timing that reflects the amount of delay generated by advance-angle timing generation means. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-268225 Summary of the Invention [Problem to be solved by the invention]

[0004] Some motor control devices control blower motors using feedback control (proportional-integral control) based on the deviation between the command rotation speed from a host ECU and the actual rotation speed of the motor. During the low-speed period from when motor control begins until the motor rotation speed reaches a predetermined value, the motor control device may use a fixed value as the command rotation speed and a fixed deviation multiplier in the proportional-integral control. However, when fixed values are used for the command rotation speed and the deviation multiplier, the speed at which the motor rotation speed increases varies depending on the ambient temperature and the inertia of the fan, resulting in unstable motor operation during the low-speed period.

[0005] One disclosed object is to provide a motor control device that can stabilize the operation of a motor during low speed periods. [Means for solving the problem]

[0006] The motor control device disclosed herein comprises: a calculation step (S18) of calculating an output duty ratio using a proportional term and an integral term according to a deviation between a command rotation speed for the motor and an actual rotation speed that is an actual rotation speed of the motor; and a driving step (S19) of driving the inverter circuit at the calculated output duty ratio to control the motor, a low-speed period determination step (S20) of determining whether or not the low-speed period is in progress from when control of the motor is started in response to a start command until the rotation speed of the motor reaches a predetermined low-speed rotation speed; A motor control device comprising setting steps (S16a, S16b, S17a to S17c) for setting a deviation magnification factor by which the proportional term and the integral term are multiplied, or a correlation value correlated to the deviation magnification factor, and when it is determined that the period is low speed, setting a deviation magnification factor or correlation value that results in a higher output duty ratio when the actual rotation speed is increasing slowly than when the increasing speed is fast, depending on the rate of increase of the actual rotation speed.

[0007] As a result, during the low-speed period, the motor control device calculates a higher output duty ratio when the actual rotation speed is increasing slowly than when it is increasing quickly, allowing the motor control device to control the motor in accordance with the rate of increase of the actual rotation speed, thereby stabilizing the operation of the motor during the low-speed period.

[0008] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a schematic configuration of a motor control device according to a first embodiment. [Figure 2] 4 is a flowchart showing the processing operation of the motor control device in the first embodiment. [Figure 3] FIG. 2 is a block diagram showing an output of a position sensor. [Figure 4] 10 is a flowchart showing the processing operation of a motor control device in a second embodiment. [Figure 5] 10 is a flowchart showing the processing operation of the motor control device in Modification 1. [Figure 6] 10 is a flowchart showing the processing operation of a motor control device in a third embodiment. [Figure 7] 10 is a time chart showing a deviation magnification and a command rotation speed in the third embodiment. [Figure 8] 10 is a flowchart showing the processing operation of a motor control device in a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment may be assigned the same reference numerals, and duplicated explanations may be omitted. In each embodiment, when only a part of the configuration is described, the other parts of the configuration may be applied by referring to the other embodiment described previously.

[0011] (First embodiment) A motor control device of a first embodiment will be described with reference to Figures 1 to 3. In this embodiment, the motor control device is applied to an ECU 200. The ECU 200 is applied to a motor unit of a so-called blower motor used to blow air in a vehicle air conditioner. The motor unit is configured to be mountable on a vehicle. The motor unit mainly includes the ECU 200 and a motor 300. ECU is an abbreviation for Electronic Control Unit.

[0012] Motor 300 is a three-phase motor including stator 310 and a rotor. Stator 310 is an electromagnet with a conductor wound around a core member, and includes three phases: U, V, and W. In other words, stator 310 includes a three-phase stator coil. Each of the U, V, and W phases of stator 310 generates a so-called rotating magnetic field by switching the polarity of the magnetic field generated by the electromagnet under the control of ECU 200, which will be described later. Note that in this disclosure, for convenience, rotation of the rotor is referred to as rotation of motor 300.

[0013] A rotor magnet 320 is provided inside the rotor. Rotor magnet 320 rotates the rotor by responding to the rotating magnetic field generated by stator 310. A shaft is provided on the rotor. The shaft rotates integrally with the rotor. A fan is provided on the shaft. When the rotor of the motor unit rotates, the fan rotates together with the shaft, enabling the vehicle air conditioner to blow air.

[0014] <Overall structure> Referring to FIG. 1, ECU 200 is electrically connected to motor 300, air conditioner ECU 500, and battery 600. Air conditioner ECU 500 is an electronic control unit for a vehicle air conditioner. Air conditioner ECU 500 outputs an SI-on signal for turning on the vehicle air conditioner in response to a user operation. Furthermore, when the user adjusts the air volume of the vehicle air conditioner, air conditioner ECU 500 outputs an SI command signal (SI signal) for instructing the rotation speed of motor 300 (rotor). Battery 600 is an on-board battery that is mounted in the vehicle together with ECU 200 and motor 300. Battery 600 supplies power to ECU 200, three-phase inverter 110, motor 300, etc.

[0015] The ECU 200 is also electrically connected to a Hall IC 400. The Hall IC 400 outputs a sensor signal that changes in response to the rotation of the motor 300 (rotor magnet 320). The Hall IC 400 includes three sensor elements, a U-phase sensor element, a V-phase sensor element, and a W-phase sensor element, to output sensor signals corresponding to the stator coils of each phase. Thus, the Hall IC 400 outputs pulse wave sensor signals for each of the U-phase, V-phase, and W-phase. The Hall IC 400 is also referred to as a position sensor. Note that the present disclosure is not limited to the Hall IC 400, and a Hall element may also be employed.

[0016] <ecu200> The ECU 200 includes a logic IC 100, a three-phase inverter 110, a choke coil 120, smoothing capacitors 131 and 132, a thermistor 140, a shunt resistor 150, etc. The ECU 200 includes a +B terminal connected to the positive electrode of the battery 600, a GND terminal connected to the negative electrode of the battery 600, and an SI terminal connected to the air conditioner ECU 500. The ECU 200 also includes a U-phase terminal, a V-phase terminal, and a W-phase terminal connected to each stator coil of the stator 310.

[0017] The three-phase inverter 110 switches the power supplied to the coils of the stator 310 using a plurality of switching elements 110A to 110F. The gate terminals of the switching elements 110A to 110F are connected to the driver 50. Therefore, the switching elements 110A to 110F are on / off controlled (switching controlled) by the driver 50. The three-phase inverter 110 is also connected to a U-phase terminal, a V-phase terminal, and a W-phase terminal.

[0018] For example, the switching elements 110A and 110D switch the power supplied to the U-phase coil 14U, the switching elements 110B and 110E switch the power supplied to the V-phase coil 14V, and the switching elements 110C and 110F switch the power supplied to the W-phase coil 14W.

[0019] The drain terminals of the switching elements 110A, 110B, and 110C are connected to one end of the choke coil 120. The other end of the choke coil 120 is connected to the +B terminal. Thus, the drain terminals are connected to the positive electrode of the battery 600 via the choke coil 120.

[0020] The source terminals of the switching elements 110D, 110E, and 110F are connected to one end of a shunt resistor 150. The other end of the shunt resistor 150 is connected to the GND terminal. Thus, the source terminals of the switching elements 110D, 110E, and 110F are connected to the negative electrode of the battery 600 via the shunt resistor 150.

[0021] Smoothing capacitors 131 and 132 are connected to both ends of choke coil 120. Choke coil 120 is also connected to air conditioner ECU 500 and battery 600. It can be said that choke coil 120 and smoothing capacitors 131 and 132, together with battery 600, constitute a DC power supply.

[0022] The logic IC 100 includes a control unit 10, a command rotation speed calculation unit 21, a forced command unit 22, a switch unit 23, a comparator 31, an actual rotation speed calculation unit 32, a voltage correction unit 40, a driver 50, an overcurrent protection circuit, an overheat protection circuit, a standby circuit 81, a main power supply energization unit 82, and an energization control unit 83. The logic IC 100 further includes a thermistor 140 and a shunt resistor 150.

[0023] Command rotation speed calculation unit 21 calculates an SI command value (variable value) based on the SI command signal from air conditioner ECU 500, as a candidate value for the command rotation speed for motor 300. Command rotation speed calculation unit 21 outputs the SI command value to switch unit 23.

[0024] The forcing command unit 22 outputs a fixed rotation speed (fixed value) as a candidate value for the command rotation speed for the motor 300. The forcing command unit 22 outputs the fixed rotation speed to the switch unit 23. Here, 500 rpm is used as an example of the fixed rotation speed.

[0025] The switch unit 23 is a switch that switches the connection with the control unit 10 between the command rotation speed calculation unit 21 and the forced command unit 22. The switch unit 23 switches the connection depending on whether or not it is in the low-speed period. The switch unit 23 is controlled by, for example, the control unit 10. The low-speed period is the period from when control of the motor 300 begins in response to a start command until the rotation speed (actual rotation speed) of the motor 300 reaches a predetermined low-speed rotation speed. The control unit 10 can consider that a start command has been issued when an SI-on signal is input. The low-speed rotation speed can be, for example, 500 rpm.

[0026] The control unit 10 considers the motor 300 to be in the startup state from the time the SI-on signal is input until the rotation speed (actual rotation speed) of the motor 300 reaches the startup rotation speed. The startup rotation speed may be, for example, 244 rpm. The actual rotation speed is the actual rotation speed of the motor 300, and can be calculated from the sensor signal from the Hall IC 400.

[0027] When the period is not the low speed period, switch unit 23 is controlled so as to connect control unit 10 to command rotation speed calculation unit 21. When the period is not the low speed period, switch unit 23 is controlled so as to connect control unit 10 to forced command unit 22. Therefore, when the period is not the low speed period, control unit 10 receives an SI command value as the command rotation speed, and when the period is the low speed period, control unit 10 receives a fixed rotation speed as the command rotation speed.

[0028] The comparator 31 converts the analog output of the Hall IC 400 into a digital signal. The comparator 31 outputs the digital signal to the control unit 10 and the actual rotation speed calculation unit 32. The actual rotation speed calculation unit 32 calculates the actual rotation speed of the rotor based on the digital signal output by the comparator 31.

[0029] The voltage corrector 40 corrects the output duty ratio based on the calculation result by the PI controller 12 (described later) in accordance with the voltage of the battery 600, which is the power source. The voltage corrector 40 then outputs the corrected final output duty ratio to the driver 50. This correction suppresses fluctuations in the rotation speed of the motor 300 when the voltage of the battery 600 fluctuates.

[0030] The driver 50 generates a PWM signal for controlling the switching of the three-phase inverter 110 based on the output duty ratio output by the voltage correction unit 40 and a drive waveform determined by an energization control unit 83 (described later), and outputs the PWM signal to the three-phase inverter 110. The three-phase inverter 110 then switches on and off the switching elements 110A to 110F in accordance with the PWM signal output by the driver 50, thereby generating a voltage to be applied to the motor 300.

[0031] The overcurrent protection circuit includes an amplifier 61, a judgment value output unit 62, a comparison unit 63, and a shunt resistor 150. The overcurrent protection circuit detects the current of the three-phase inverter 110, and instructs the driver 50 to stop output when the current exceeds an overcurrent judgment value. The amplifier 61 detects the potential difference across the shunt resistor 150, which changes depending on the current of the three-phase inverter 110, and amplifies a signal of the detected potential difference. The signal output by the amplifier 61 is input to the comparison unit 63.

[0032] The comparison unit 63 compares the signal output by the amplifier 61 with the overcurrent determination value output by the determination value output unit 62. If the signal output by the amplifier 61 is equal to or greater than the overcurrent determination value, the comparison unit 63 outputs an overcurrent detection signal to the driver 50. The overcurrent detection signal is a signal that indicates an output stop instruction. By outputting the overcurrent detection signal, the comparison unit 63 controls the driver 50 to stop the supply of current to the motor 300. This stops the rotation of the motor 300 and protects the elements that make up the three-phase inverter 110, etc.

[0033] The overheat protection circuit includes a judgment value output unit 71, a comparison unit 72, and a thermistor 140. The thermistor 140 forms a kind of voltage dividing circuit. A voltage that varies based on the resistance value of the thermistor 140 is output from the output terminal of the voltage dividing circuit formed by the thermistor 140.

[0034] The voltage output from thermistor 140 is input to comparison unit 72. Comparison unit 72 compares the voltage output from thermistor 140 with the overheating determination value output by determination value output unit 71. If the magnitude relationship between the voltage output from thermistor 140 and the overheating determination value indicates overheating, comparison unit 72 controls command rotation speed calculation unit 21 to forcibly set the command rotation speed to 0 rpm.

[0035] Standby circuit 81 is a circuit that controls the power supply from battery 600 to each unit. Main power supply unit 82 turns on the power supply to ECU 200 under the control of standby circuit 81. When motor 300 is started, main power supply unit 82 controls forcing command unit 22 to output a fixed rotation speed for a predetermined time. After the predetermined time has elapsed, main power supply unit 82 stops the output of the fixed rotation speed by forcing command unit 22. After the predetermined time has elapsed, control unit 10 performs PI control using an SI command value based on an instruction from air conditioner ECU 500. The predetermined time is a time that can be considered a low-speed period.

[0036] When power is supplied via the standby circuit 81 and the main power supply unit 82, the current control unit 83 determines the drive waveform of the voltage to be applied to the coil of the stator 310 based on the signal from the voltage correction unit 40. The current control unit 83 also switches the current supply period.

[0037] The control unit 10 includes a processor, a memory device, an input / output interface, etc. The processor performs various arithmetic processing by executing programs stored in the memory device. The control unit 10 can also be said to have a plurality of functional blocks that can be executed by the arithmetic processing of the processor. The control unit 10 includes a deviation magnification calculation unit 11, a PI control unit 12, and a time calculation unit 13 as examples of functional blocks.

[0038] The deviation magnification factor used in the PI control unit 12, which will be explained later, is calculated. The deviation magnification factor calculation unit 11 calculates (sets) a deviation magnification factor that results in a higher output duty ratio when the increase rate of the actual rotation speed is slow compared to when it is fast during the low-speed period. In this embodiment, the deviation magnification factor calculation unit 11 calculates the deviation magnification factor A from the ratio of the elapsed time to the reference time.

[0039] Here, a method for calculating the deviation magnification A will be described with reference to Figure 3. Figure 3 shows the change over time in the output of the position sensor. The position sensor output in the upper row shows the output when the rotation increase of the motor 300 is not slow and is the reference rotation increase. The position sensor output in the lower row shows the output when the rotation increase of the motor 300 is slow. Here, the position sensor output in the lower row is the position sensor output for the actual motor 300. The rotation increase of the motor 300 can also be said to be the rate of increase in the actual rotation speed of the motor 300.

[0040] ECU 200 starts controlling motor 300 upon receiving an SI-on signal at timing t1. The first rising edge of the position sensor output, such as timing t2, indicates the start of rotation of motor 300. The period between rising edges, such as timings t2 and t3, indicates one electrical angle cycle. Here, a 10-pole motor 300 is used as an example. Therefore, timings t4 and t5 indicate one rotation of motor 300 (five electrical angle cycles). Hereinafter, one rotation of motor 300 will also be referred to as one motor rotation.

[0041] The deviation magnification factor A is obtained by multiplying the elapsed time p1 / reference time p0 by a constant K and a reference value of the deviation magnification factor. The reference time p0 is the time required for the motor 300 to make one rotation from the SI-ON signal in the reference position sensor output. The elapsed time p1 is the time required for the motor to make one rotation from the SI-ON signal, as measured by the time calculation unit 13. It can be said that the control unit 10 determines the rate of increase of the actual rotation speed by calculating the elapsed time p1 / reference time p0. It can also be said that the control unit 10 determines the rate of increase of the actual rotation speed based on the time from the SI-ON signal to one rotation of the motor.

[0042] In the present disclosure, the rate of increase in the actual rotation speed may be determined based on the time from the SI-on signal to the start of rotation or the time from the SI-on signal to one electrical angle cycle. Furthermore, in the present disclosure, the rate of increase in the actual rotation speed may be determined based on the time from the start of rotation of the motor 300 to one electrical angle cycle or the time from the start of rotation of the motor 300 to one rotation of the motor 300.

[0043] In this manner, in this embodiment, the rate of increase in the actual rotation speed is determined based on the elapsed time. Therefore, in this embodiment, the rate of increase in the actual rotation speed can be directly determined. Therefore, in this embodiment, an optimal deviation magnification A corresponding to the actual operation of the motor 300 can be calculated.

[0044] The control unit 10 preferably determines the rising speed based on the time from the SI-on signal to one rotation of the motor, thereby being able to calculate the deviation magnification A with reduced variation in the rising speed. Also, the control unit 10 preferably determines the rising speed based on the time from the SI-on signal to one electrical angle cycle, thereby being able to calculate the deviation magnification A at an early timing. Note that the control unit 10 can ascertain the start of rotation, one motor rotation, one electrical angle cycle, etc. by detecting edges of the digital signal input from the comparator 31.

[0045] The PI control unit 12 calculates, by PI control, an output duty ratio (PIDuty) of a voltage to be applied to the coil of the stator 310 when changing the actual rotation speed to the target rotation speed, from the target rotation speed calculated by the command rotation speed calculation unit 21 and the actual rotation speed calculated by the actual rotation speed calculation unit 32.

[0046]

number

[0047] <Processing operation> The processing operation of ECU 200 will be described with reference to Fig. 2. When an SI-on signal is input from air conditioner ECU 500 (SI command input), ECU 200 starts the processing shown in the flowchart of Fig. 2.

[0048] In step S10, the control unit 10 starts energizing the motor 300 via the three-phase inverter 110.

[0049] In step S11, it is determined whether or not it is startup time. If the actual rotation speed of the motor 300 has not reached the startup rotation speed, the control unit 10 determines that it is startup time, and proceeds to step S12a. If the actual rotation speed of the motor 300 has reached the startup rotation speed, the control unit 10 determines that it is not startup time, and proceeds to step S21. Note that while the control unit 10 makes a YES determination in step S11 and a NO determination in step S20, which will be described later, it proceeds to step S12a. Steps S12a to S20 can be said to be processes executed during the low speed period.

[0050] In step S12a, it is determined whether the motor has rotated one revolution after the start command. If the control unit 10 determines that the motor has rotated one revolution after the SI-on signal is input, the control unit 10 proceeds to step S15, and if it determines that the motor has not rotated one revolution, the control unit 10 proceeds to step S13.

[0051] In step S13, the command rotation speed is set to 500 rpm (fixed rotation speed). The control unit 10 controls the switch unit 23 so that the control unit 10 is connected to the forcing command unit 22. Therefore, the fixed rotation speed is input to the control unit 10 as the command rotation speed.

[0052] In step S14, the deviation magnification is set to 8x. The control unit 10 sets the deviation magnification to 8x. 8x is the reference value of the deviation magnification. Note that 8x is used here as an example. However, the present disclosure is not limited to this. Any fixed magnification that can improve the feeling at startup, that is, that can stabilize the operation of the motor 300, can be used here. In this way, the control unit 10 uses the reference value of the deviation magnification from the input of the SI-on signal until the motor rotates one revolution. In other words, the control unit 10 uses the reference value as the deviation magnification during the period until it becomes possible to calculate the deviation magnification A.

[0053] Step S15 is the same as step S13. Step S16a calculates the deviation magnification A (setting step). The deviation magnification calculation unit 11 calculates the deviation magnification A as described above. That is, when it determines that the period is a low-speed period, the deviation magnification calculation unit 11 sets the deviation magnification A in accordance with the rate of increase of the actual rotation speed, so that the output duty ratio is higher when the rate of increase of the actual rotation speed is slow than when it is fast. Here, as an example, the deviation magnification A is calculated from the ratio of the elapsed time p1 required from the reception of the SI-on signal until the motor makes one rotation to the reference time p0 related to the elapsed time.

[0054] In step S17a, the deviation magnification is set to A (setting step). The deviation magnification calculation unit 11 sets A as the deviation magnification used in the PI calculation in step S18.

[0055] In step S18, a PI calculation is performed (a calculation step). As described above, the PI control unit 12 calculates the output duty ratio using a proportional term and an integral term according to the deviation between the command rotation speed for the motor 300 and the actual rotation speed of the motor 300. When steps S13 and S14 are performed, the PI control unit 12 performs the PI calculation using 500 rpm as the command rotation speed and 8 times as the deviation magnification. On the other hand, when steps S15, S16a, and S17a are performed, the PI control unit 12 performs the PI calculation using 500 rpm as the command rotation speed and A times as the deviation magnification.

[0056] In step S19, the three-phase inverter is driven (driving step). The control unit 10 drives the three-phase inverter 110 with the calculated output duty ratio to control the motor 300. Note that in this embodiment, an example is adopted in which the output duty ratio is corrected by the voltage correction unit 40 in accordance with the voltage of the battery 600, as described above. However, in the present disclosure, the correction by the voltage correction unit 40 can also be omitted.

[0057] In step S20, it is determined whether the rotation speed is ≧500 rpm (low speed period determination step). The control unit 10 determines whether it is a low speed period from when control of the motor 300 is started in response to the SI-on signal until the rotation speed of the motor 300 reaches the low speed rotation speed (500 rpm). If the control unit 10 determines that the rotation speed is ≧500 rpm, it considers that it is not a low speed period and proceeds to step S21. If the control unit 10 determines that the rotation speed is not ≧500 rpm, it considers that it is a low speed period and returns to step S12a.

[0058] In step S21, normal driving is performed. The control unit 10 controls the switch unit 23 so that the control unit 10 and the command rotation speed calculation unit 21 are connected. Therefore, the control unit 10 receives an SI command value as the command rotation speed. Therefore, the PI control unit 12 calculates an output duty ratio using a proportional term and an integral term according to the deviation between the SI command value, which is the command rotation speed for the motor 300, and the actual rotation speed of the motor 300. At this time, the PI control unit 12 uses 1 as the deviation magnification. Then, similar to step S19, the control unit 10 drives the three-phase inverter 110 with the calculated output duty ratio to control the motor 300.

[0059] <Effects> As described above, during the low-speed period, the ECU 200 calculates a higher output duty ratio when the actual rotation speed is increasing slowly than when it is increasing quickly, depending on the rate of increase in the actual rotation speed. This allows the ECU 200 to control the motor 300 in accordance with the rate of increase in the actual rotation speed. This allows the ECU 200 to stabilize the operation of the motor 300 during the low-speed period. In other words, the ECU 200 can ensure a stable startup feeling even when it is difficult to increase the rotation speed due to the influence of inertia or temperature.

[0060] The preferred embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the present disclosure. Below, second to fourth embodiments will be described as other aspects of the present disclosure. The above embodiments and the second to fourth embodiments can be implemented independently, or can be implemented in appropriate combinations. The present disclosure is not limited to the combinations shown in the embodiments, and can be implemented in various combinations.

[0061] (Second embodiment) The ECU 200 of the second embodiment will be described with reference to Fig. 4. Here, differences from the first embodiment will be mainly described. The present embodiment differs from the first embodiment in processing operations. In Fig. 4, the same processes as in Fig. 2 are assigned the same step numbers as in Fig. 2.

[0062] The rate of increase of the actual rotation speed slows as the ambient temperature of the motor 300 decreases. Therefore, the deviation magnification calculation unit 11 calculates the deviation magnification B from the ratio between the measured temperature correlated with the ambient temperature of the motor 300 and a reference temperature related to the ambient temperature. That is, in this embodiment, the deviation magnification B is a value calculated according to the temperature. Furthermore, the deviation magnification calculation unit 11 changes the deviation magnification according to the temperature. The ambient temperature can be detected based on an output signal from the thermistor 140 or the like.

[0063] When the ECU 200 receives the SI-on signal from the air conditioner ECU 500, the ECU 200 starts the process shown in the flowchart of FIG.

[0064] In step S16b, the deviation magnification factor B is calculated (setting step). The deviation magnification factor B is obtained by multiplying the reference temperature T0°C / measured temperature T°C by a constant K and the reference value of the deviation magnification factor. The reference temperature T0 is a reference temperature. For example, the reference temperature T0 can be a temperature at which the reference increase in rotation speed of the motor 300 is obtained. The measured temperature T is the current ambient temperature measured around the motor 300. The deviation magnification factor calculation unit 11 calculates the deviation magnification factor B so that it increases as the ambient temperature decreases. In other words, when the deviation magnification calculation unit 11 determines that the low-speed period is occurring, it sets the deviation magnification factor B according to the rate of increase of the actual rotation speed using the ambient temperature, such that the output duty ratio is higher when the rate of increase of the actual rotation speed is slower than when it is fast. In this way, it can be said that the deviation magnification factor calculation unit 11 indirectly determines the rate of increase of the actual rotation speed using the ambient temperature.

[0065] In step S17b, the deviation magnification is set to B (setting step). The deviation magnification calculation unit 11 sets B as the deviation magnification used in the PI calculation in step S18. The PI control unit 12 uses B instead of A in step S18.

[0066] The ECU 200 of this embodiment can achieve the same effects as the above-described embodiment. Furthermore, the ECU 200 of this embodiment can set the deviation magnification B by detecting the ambient temperature based on an output signal from the thermistor 140 or the like and performing the above calculation. Therefore, the ECU 200 of this embodiment can simplify the processing by eliminating the need to detect an edge or measure the elapsed time from the edge.

[0067] (Variation) Also, as shown in Fig. 5, the deviation magnification may be variable only at low temperatures, and fixed to a reference value at temperatures above a certain level. In Fig. 5, the same steps as in Figs. 2 and 4 are assigned the same step numbers.

[0068] In step S12b, the control unit 10 determines whether the ambient temperature is equal to or lower than the low temperature X1°C. If the control unit 10 determines that the ambient temperature is equal to or lower than the low temperature X1°C, it determines that the increase in rotation speed of the motor 300 will slow down, and proceeds to step S15. If the control unit 10 determines that the ambient temperature is not equal to or lower than the low temperature X1°C, it determines that the increase in rotation speed of the motor 300 will not slow down, and proceeds to step S13. The low temperature X1 is a temperature at which the increase in rotation speed of the motor 300 is considered to slow down. The low temperature X1 can be set in advance by experiment, simulation, or the like. This allows the modification to reduce the calculation process of the deviation magnification B by the control unit 10.

[0069] (Third embodiment) The ECU 200 of the third embodiment will be described with reference to Figures 6 and 7. Here, differences from the first embodiment will be mainly described. This embodiment differs from the first embodiment in processing operations. In Figure 6, the same processes as in Figure 2 are assigned the same step numbers as in Figure 2.

[0070] FIG. 7 shows the deviation magnification, command rotation speed, and time changes in rotation speed. p10 (timing t11 to t13) indicates the lock protection activation time. p11 (timing t11 to t12) is the period for determining whether or not to change the deviation magnification. p11 is set to a time shorter than the normal lock protection activation time (p10). Furthermore, timing t1 is the timing when the SI-on signal is input. Timing t14 is the timing when switching to normal drive.

[0071] If the motor 300 does not start rotating within a predetermined period p11 after receiving the SI-on signal, the rate of increase in the actual rotation speed can be considered slow. This can occur, for example, when lock protection is activated. In the example of FIG. 7, lock protection is activated if the motor 300 does not rotate during the period p10 from receiving the SI-on signal to timing t13. Therefore, the control unit 10 sets a deviation magnification such that, if the motor 300 does not start rotating within the predetermined period p11 after receiving the SI-on signal, the output duty ratio is higher than if the motor 300 starts rotating within the predetermined period p11. Note that if the motor 300 is deteriorated, the motor 300 may not start rotating within the predetermined period p11 after receiving the SI-on signal, even if the ambient temperature of the motor 300 is low.

[0072] Therefore, in step S12c, it is determined whether rotation has started within the time p11 has elapsed. If the control unit 10 determines that rotation has started within the time p11 has elapsed, the process proceeds to step S13. In this case, the deviation magnification becomes 8 times as shown at timings t11 to t12. On the other hand, if the control unit 10 determines that rotation has not started within the time p11 has elapsed, the process proceeds to step S15, assuming that the increase in rotation (increase speed) is slow. The control unit 10 can determine whether the motor 300 has started to rotate based on the sensor signal from the Hall IC 400.

[0073] In step S17c, the deviation magnification is set to C (setting step). As shown at timings t11 to t12, the deviation magnification calculation unit 11 sets a fixed value C as the deviation magnification without calculating the deviation magnification. C can be a value greater than 8, such as 16. If the determination of NO continues in step S20, the deviation magnification calculation unit 11 may gradually change the deviation magnification C to a larger value. In other words, if the motor 300 does not start rotating even after setting the deviation magnification in step S17c, the deviation magnification calculation unit 11 may switch the deviation magnification multiple times within the activation time of the lock protection. The PI control unit 12 uses C instead of A in equation 1.

[0074] In this way, when it is determined that the period is a low speed period, the deviation magnification calculation unit 11 sets the deviation magnification C in accordance with the rate of increase of the actual rotation speed so that the output duty ratio is higher when the rate of increase of the actual rotation speed is slow than when it is fast. Also, it can be said that the deviation magnification calculation unit 11 indirectly determines the rate of increase of the actual rotation speed based on whether or not the motor 300 starts rotating during the lapse of the predetermined period p11.

[0075] The ECU 200 of this embodiment can achieve the same effects as those of the first embodiment. Furthermore, the ECU 200 of this embodiment can set the deviation magnification even when the motor 300 is not rotating.

[0076] (Fourth embodiment) The ECU 200 of the fourth embodiment will be described with reference to Fig. 8. Here, differences from the first embodiment will be mainly described. This embodiment differs from the first embodiment in processing operations. In Fig. 8, the same processes as in Fig. 2 are assigned the same step numbers as in Fig. 2.

[0077] In step S18, the control unit 10 calculates the output duty ratio using the cumulative deviation, which is the cumulative value of the deviation magnification. To this end, in step S30, the control unit 10 calculates the cumulative deviation and the upper limit value (cumulative deviation determination step). The control unit 10 calculates the cumulative deviation by adding the new deviation magnification to the current cumulative deviation. The control unit 10 also calculates the upper limit value by calculating upper limit value=(K1×N+K2)×1 / power supply voltage, where power supply voltage is the voltage of the battery 600. In the formula representing the upper limit value, N is the rotation speed [rpm], and K1 and K2 are constants.

[0078] In step S31, it is determined whether the cumulative deviation is greater than the upper limit (accumulation deviation determination step). If the control unit 10 determines that the cumulative deviation is greater than the upper limit, the process proceeds to step S32, and if it determines that the cumulative deviation is not greater than the upper limit, the process proceeds to step S18.

[0079] In step S32, the deviation accumulation is stopped (accumulated deviation determination step). When the control unit 10 determines that the accumulated deviation exceeds the upper limit, it stops accumulating the deviation magnification. Therefore, in this case, the control unit 10 performs the PI calculation using the accumulated deviation up to the previous time.

[0080] The ECU 200 of this embodiment can suppress excessive output caused by excessive cumulative deviation, and can prevent shutdown due to overcurrent protection.

[0081] The control unit 10 may set an upper limit on the output duty value instead of the cumulative deviation. This can also achieve the same effect. The upper limit value is set so that the upper limit of the current of the motor 300 is a current value equal to or less than the overcurrent protection threshold. The technology described in the fourth embodiment can be applied to each of the first to third embodiments. For example, the ECU 200 of this embodiment can achieve the same effect as the first embodiment by being implemented in combination with the first embodiment.

[0082] In the first to fourth embodiments, an example is adopted in which a deviation magnification is set so that the output duty ratio is higher when the rising speed is slow than when it is fast. However, the present disclosure is not limited to this. In place of the deviation magnification, the present disclosure may use a correlation value correlated to the deviation magnification. In other words, the present disclosure sets a correlation value so that the output duty ratio is higher when the rising speed is slow than when it is fast. The correlation value may be changed by changing the command rotation speed or the gains (Kp, Ki) in PI control.

[0083] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, although various combinations and forms are shown in the present disclosure, other combinations and forms including only one element, more, or less than one element are also within the scope and spirit of the present disclosure. [Explanation of symbols]

[0084] 10...control unit, 11...deviation magnification calculation unit, 12...PI control unit, 13...time calculation unit, 21...SI command value calculation unit, 22...forced command unit, 23...switch unit, 31...comparator, 32...actual rotation speed calculation unit, 40...voltage correction unit, 50...driver, 61...amplifier, 62...judgment value input unit, 63...comparison unit, 71...judgment value input unit, 72...comparison unit, 81...standby circuit, 82...main power supply energization unit, 83...energization control unit, 100...logic IC, 110...three-phase inverter, 120...choke coil, 131, 132...smoothing capacitor, 140...thermistor, 150...shunt resistor, 200...ECU, 300...motor, 310...stator, 320...rotor magnet, 400...Hall IC, 500...air conditioner ECU

Claims

1. a calculation step (S18) of calculating an output duty ratio using a proportional term and an integral term in accordance with a deviation between a command rotation speed for the motor and an actual rotation speed that is an actual rotation speed of the motor; a driving step (S19) of driving an inverter circuit at the calculated output duty ratio to control the motor, a low-speed period determination step (S20) of determining whether or not the low-speed period is in progress from when control of the motor is started in response to a start command until the rotation speed of the motor reaches a predetermined low-speed rotation speed; and setting steps (S16a, S16b, S17a to S17c) of setting a deviation magnification by which the proportional term and the integral term are multiplied, or a correlation value correlated to the deviation magnification, and when it is determined that the low-speed period is occurring, setting the deviation magnification or the correlation value in accordance with the rate of increase of the actual rotation speed so that the output duty ratio is higher when the rate of increase is slow than when the rate of increase is fast, in accordance with the rate of increase of the actual rotation speed.

2. 2. The motor control device according to claim 1, wherein the setting step calculates the deviation magnification or the correlation value from a ratio of an elapsed time required for the motor to rotate once from the reception of the start command to a reference time related to the elapsed time.

3. 2. The motor control device according to claim 1, wherein the setting step calculates the deviation magnification or the correlation value from a ratio between a measured temperature correlated with the ambient temperature of the motor and a reference temperature related to the ambient temperature.

4. 2. The motor control device according to claim 1, wherein, in the setting step, if the motor does not start rotating within a predetermined period of time from receiving the start command, the deviation magnification or the correlation value is set so that the output duty ratio is higher than when the motor starts rotating within the predetermined period of time.

5. In the calculation step, the output duty ratio is calculated using an accumulated deviation that is an accumulated value of the deviation magnification, The motor control device according to any one of claims 1 to 4, further comprising an accumulated deviation determination step (S30 to S32) of determining whether the accumulated deviation exceeds an upper limit value, and stopping the accumulation of the deviation magnification when it is determined that the accumulated deviation exceeds the upper limit value.

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