Motor control device and motor control method

Abstract

To provide a motor control device with high reliability that can prevent a voltage shortage when reactivating a motor with a regenerative voltage in a power failure state, and can be controlled while keeping balance of headwind and motor driving after activation.SOLUTION: A motor control device comprises: a motor control circuit that controls a permanent magnet synchronous motor; and a power failure detection circuit that detects a power supply stop of DC power. If a power failure state is detected in the power failure detection circuit, the motor control circuit passes an Id current as an initial value such that 0<V1≤0.94875 ωKe (V1: a voltage command, ω: the rotation number of the motor at reactivation, and Ke: a motor generation constant) when the permanent magnet synchronous motor is generating electric power with a head wind and the permanent magnet synchronous motor is reactivated using the power generation energy.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a configuration of a motor control device and a control method thereof, and in particular to a technique that is effective when applied to an outdoor fan motor of an air conditioner, etc., in which a motor is rotated by headwind during a power outage and regenerative voltage is generated. [Background technology]

[0002] Permanent magnet synchronous motors are generally used in fan drive motors for outdoor units of air conditioners and eco-cutes, ceiling fans, ventilation fans, etc. In such applications, when a permanent magnet synchronous motor is rotated by headwind during a power outage, a regenerative voltage is generated in the permanent magnet synchronous motor.

[0003] Background art in this technical field includes, for example, technology such as that described in Patent Document 1. Patent Document 1 discloses "a motor drive device that controls the rotation speed of a motor during a power outage to keep the DC voltage constant, stably supplying power to a control circuit, etc., while simultaneously performing deceleration control of the motor to shorten the deceleration time."

[0004] Furthermore, Patent Document 2 discloses a "control device for a permanent magnet motor that enables smooth restart by performing a switching operation on the inverter so as to output a value equivalent to the no-load induced voltage of the permanent magnet motor or the inverter maximum voltage in the same direction as the no-load induced voltage before restarting the switch, and then closing the switch." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-374700 A [Patent Document 2] JP 2000-295889 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, in the motors for outdoor unit fans of air conditioners and eco-cutes, when there is a power outage, the permanent magnet synchronous motor is rotated by the reverse wind. If the motor is driven by the regenerative voltage, when attempting to drive the motor from the rotational speed at which it is being rotated by the reverse wind, there will be a voltage shortage at the moment of restart.

[0007] Also, when controlling the rotational speed, if the target rotational speed is higher than the rotational speed due to the reverse wind, the regenerative voltage decreases and motor control becomes impossible. Conversely, if the target rotational speed is lower than the rotational speed due to the reverse wind, the regenerative voltage increases and the system becomes overvoltage.

[0008] In Patent Document 1 and Patent Document 2 described above, the above problems are not fully considered and there is room for improvement.

[0009] Therefore, an object of the present invention is to provide a highly reliable motor control device and its control method that can prevent voltage shortage when restarting the motor with the regenerative voltage in a power outage state, and can control while balancing the reverse wind and motor drive after startup.

Means for Solving the Problems

[0010] To solve the above problems, the present invention includes a motor control circuit that controls a permanent magnet synchronous motor, and a power outage detection circuit that detects the stop of the supply of DC power. When the power outage detection circuit detects a power outage state, the motor control circuit, when restarting the permanent magnet synchronous motor using the power generation energy generated by the reverse wind of the permanent magnet synchronous motor, flows an Id current as an initial value so that 0<V1≦0.94875ωKe (V1: voltage command, ω: motor rotational speed at the time of restart, Ke: motor power generation constant).

[0011] Furthermore, the present invention includes: (a) a step of detecting the energized state or power failure state of a permanent magnet synchronous motor; (b) in the step (a), when detecting a power failure state, if the permanent magnet synchronous motor is generating electricity due to a reverse wind, and when restarting the permanent magnet synchronous motor using the generated energy, a step of flowing an Id current as an initial value so that 0<V1≦0.94875ωKe (V1: voltage command, ω: motor rotation speed at restart, Ke: motor generation constant).

Advantages of the Invention

[0012] According to the present invention, it is possible to prevent voltage shortage when restarting the motor with the regenerative voltage in a power failure state, and to realize a highly reliable motor control device and its control method that can be controlled while balancing the reverse wind and motor drive after startup.

[0013] As a result, the motor can be restarted with the regenerative voltage due to the reverse wind, and even in a power failure state, if there is a regenerative voltage due to the reverse wind, it becomes possible to immediately respond to overvoltage and power restoration due to a sudden increase in the reverse wind.

[0014] Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0015] [Figure 1] It is a diagram showing a schematic configuration of a motor control device according to Embodiment 1 of the present invention. [Diagram 2] It is a diagram showing the relationship between the q-axis voltage and the d-axis voltage. [Diagram 3] It is a diagram showing the configuration of the modulation rate control unit 14 in FIG. 1. [Figure 4] It is a diagram showing a configuration example of a three-phase diode rectifier circuit. [Diagram 5] It is a diagram schematically showing a regenerative operation in a power loss state. [Figure 6] It is a flowchart showing a motor control method according to Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are designated by the same reference numerals, and detailed description of overlapping parts will be omitted. EXAMPLES

[0017] First, in order to make the present invention easier to understand, regenerative operation in a power loss state will be described with reference to Fig. 5. Fig. 5 is a diagram showing a schematic diagram of regenerative operation in a power loss state in a motor for a fan in an outdoor unit of an air conditioner.

[0018] As shown in Fig. 5, when a fan 20 rotates due to external wind 19 in a state of power loss such as a blackout, an induced voltage is generated in a motor 21. The generated induced voltage is converted to a DC voltage by a circuit when the inverter section 23 of the motor driver IC 22 is OFF. When the inverter is OFF, the circuit functions equivalently to a diode rectifier. The converted DC voltage is regenerated to the upper power supply system and becomes the regenerative voltage Edc in Fig. 5.

[0019] Next, a motor control device and a motor control method according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4 and 6. FIG.

[0020] Fig. 1 is a diagram showing a schematic configuration of a motor control device 100 of this embodiment. Fig. 2 is a diagram showing the relationship between the q-axis voltage and the d-axis voltage. Fig. 3 is a diagram showing the configuration of a modulation factor control unit 14 of Fig. 1. Fig. 4 is a diagram showing an example of the configuration of a three-phase diode rectifier circuit. Fig. 6 is a flowchart showing a motor control method of this embodiment.

[0021] 1, the motor control device 100 of this embodiment mainly comprises a current detection unit 2, a coordinate conversion unit 3, a current control unit 4, a voltage command value creation unit 5, a power conversion unit 6, a magnetic pole position estimation unit 7, an induced voltage detection unit 8, a rotation speed calculation unit 9, an Edc detection unit 10, a power failure determination unit 11, a current command switching means 12, a rotation speed switching means 13, and a modulation factor control unit 14. The motor control device 100 controls the drive of a permanent magnet synchronous motor 1 connected thereto.

[0022] The phase currents Iu, Iv, and Iw flowing through the permanent magnet synchronous motor 1 are detected by the current detection unit 2, and the coordinate conversion unit 3 converts the coordinates to the dc-qc axes, which are the rotor orthogonal coordinate system, based on the magnetic pole position information, and outputs the detected currents Idc and Iqc.

[0023] Using the detected currents Idc and Iqc and the current command values ​​Id* and Iq*, the current control unit 4 causes the detected currents to follow the current command values.

[0024] The voltage command value creation unit 5 uses the output of the current control unit 4, the rotation speed information provided by the rotation speed switching means 13, and the motor constants Ke*, R*, Ld*, and Lq* to calculate voltage command values ​​Vd* and Vq* using equation (1), and calculates and outputs a voltage command V1 of the composite vector of Vd* and Vq* using equation (2).

[0025]

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[0026]

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[0027] Moreover, a magnetic pole position estimating unit 7 outputs three-phase voltage commands Vu*, Vv*, Vw* using a magnetic pole position estimate value θc calculated using the detected currents Idc, Iqc and the voltage command values ​​Vd*, Vq*.

[0028] The power conversion unit 6 turns on the output elements and applies a voltage to the permanent magnet synchronous motor 1 in accordance with the three-phase voltage commands Vu*, Vv*, and Vw*.

[0029] An induced voltage detection unit 8 detects induced voltages Eu, Ev, Ew when the power conversion unit 6 is not operating, and a rotation speed calculation unit 9 calculates the motor rotation speed ω1 at that time.

[0030] A power outage determination unit 11 determines whether or not a power outage has occurred using a value Edc1 from an Edc detection unit 10 that detects a DC voltage of the inverter and a motor rotation speed ω1 from a rotation speed calculation unit 9.

[0031] When starting the motor using the motor's regenerative voltage during a power outage, the current command switching means 12 turns on signal terminal 12S1 to output the startup initial value current commands Iq*1, Id*1 for use during a power outage, and then turns on signal terminal 12S2 to switch to outputting current command values ​​Id*2 and Iq*2.

[0032] When the motor drive is maintained by the regenerative voltage of the motor during a power outage, the rotation speed switching means 13 turns on the signal terminal 13S1 and outputs a speed command ω1_h* so that the modulation factor control unit 14 keeps the modulation factor constant.

[0033] The relationship between the q-axis voltage and the d-axis voltage will be described with reference to FIG.

[0034] The regenerative voltage due to headwind is determined by the rotation speed and the motor power generation constant Ke as follows. The motor power generation constant Ke is an inherent value of the permanent magnet synchronous motor 1.

[0035] Edc=ωKe×1.65 If the motor is rotated by a headwind of ω during a power outage, then in order to control it at the rotation speed ω at that time, it is sufficient to apply a voltage ωke that generates power at that rotation speed to the q-axis. However, the power generated by a headwind of ω is Edc = ωKe × 1.65, and with this voltage, the motor phase voltage V1 = 0.94875ωKe (ωKe × 1.65 / 2 × 1.15) can only be output.

[0036] If an attempt is made to output V1 at ωKe, a modulation ratio of 1.212 is required, which exceeds 1.15 and enters the overmodulation region, causing distortion in the line-to-line voltage waveform of the motor.

[0037] Therefore, as shown in Fig. 2, at startup, Id is set to the initial value for power failure startup 15 such that 0 < V1 ≤ 0.94875ωKe, compensating for the voltage shortage.

[0038] Using Fig. 3, the modulation ratio constant control will be described.

[0039] After the motor is started by the regenerative energy during a power failure, the signal terminal 12S2 of the current command switching means 12 is turned ON, and the current command values Id*2 and Iq*2 are output. At this time, Id*2 = 0.

[0040] Then, in the modulation ratio control unit 14, the modulation ratio is controlled to achieve the target modulation ratio.

[0041] Specifically, taking the motor speed at startup as the initial value ω1*_init, and using the regenerative voltage generated by the reverse wind to enable motor drive, the modulation ratio target value is set to 0 < kH* ≤ 0.94875, and the target speed command value is determined so that the deviation between the set modulation ratio target value and the actual modulation ratio becomes zero.

[0042] First, in the modulation ratio calculation unit 16, the modulation ratio kH is calculated by Equation (3) using Edc1 detected by the Edc detection unit 10 and V1 calculated by the voltage command value creation unit 5.

[0043]

Equation

[0044] The modulation ratio target value 17 is set to 0 < kH* ≤ 0.94875 (1.65 / 2 × 1.15) so that the voltage does not become insufficient and the motor can be driven by the regenerative energy due to the reverse wind.

[0045] A rotation speed command Δω is calculated so that the deviation between kH and KH* becomes 0, and is added to the motor rotation speed initial value ω1*_init at the time of startup to calculate the rotation speed target value ω1*.

[0046] As a result, when a headwind is blowing during a power outage, the motor can be maintained in a driven state while using the regenerative voltage generated by the headwind.

[0047] A method for determining the power loss state will be described with reference to FIG.

[0048] When applying the present invention, there is a problem in that it is difficult to distinguish between the DC voltage value in the "power loss + regenerative operation" state and the "normal power restored" state.

[0049] Therefore, in this invention, the theoretical value of the regenerative voltage when the inverter is not operating is calculated from the induced voltage constant and the detected speed value.The theoretical value of the regenerative voltage is then compared with the detected DC voltage value, and if the two values ​​are close to each other, it is determined that the state is "power loss + regenerative operation", and if they are far apart, it is determined that the state is "normal power restored".

[0050] The theoretical value of the regenerative voltage is calculated by using the diode rectifier circuit shown in Figure 4 as an example to calculate the average DC voltage Edc (DC voltage detection value) generated by the regenerative operation.

[0051] The induced voltages v1, v2, and v3 generated in the three-phase lines of the motor are expressed as shown in equations (4) to (6) using the peak value V_p [V] and phase Ωt of the induced voltages.

[0052]

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[0053]

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[0054]

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[0055] In this case, the DC voltage average value Edc is expressed as shown in equation (7).

[0056]

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[0057] In addition, when the induced voltage constant Ke [Vpeak / (rad / s)] and the detected speed value F [Hz] are used, V_p=2πF×Ke is obtained, and this is expressed by equations (8) and (9).

[0058]

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[0059]

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[0060] The basic motor control method of the present invention will be described with reference to FIG.

[0061] First, in step S1, the energized state or power outage state of the permanent magnet synchronous motor 1 is detected.

[0062] If a power outage is detected, the process proceeds to step S2, where it is determined whether or not the permanent magnet synchronous motor 1 is generating power due to headwind. On the other hand, if a power-on state is detected, the process ends.

[0063] Next, in step S2, if it is determined that the permanent magnet synchronous motor 1 is generating power due to headwind, the process proceeds to step S3, where an Id current is passed as an initial value so that 0<motor phase voltage V1≦0.94875ωKe is satisfied when restarting the permanent magnet synchronous motor 1 using the generated energy in step S2. On the other hand, if it is determined that the permanent magnet synchronous motor 1 is not generating power due to headwind, the process ends.

[0064] Finally, in step S4, the permanent magnet synchronous motor 1 is restarted, and the process ends.

[0065] As described above, the motor control device 100 of the present embodiment includes a motor control circuit that controls the permanent magnet synchronous motor 1 and a power failure detection circuit (power failure determination unit 11) that detects the stop of the DC power supply. When the power failure detection circuit (power failure determination unit 11) detects a power failure state, the motor control circuit makes the permanent magnet synchronous motor 1 generate electricity due to the reverse wind, and when restarting the permanent magnet synchronous motor 1 using the generated energy, an Id current is passed as an initial value so that 0 < motor phase voltage V1 ≤ 0.94875ωKe (V1: voltage command, ω: motor rotation speed when restarting, Ke: motor generation constant).

[0066] This prevents a voltage shortage when restarting the motor with the regenerative voltage in the power failure state, and enables the motor to be reliably restarted with the regenerative voltage due to the reverse wind.

[0067] Also, after the permanent magnet synchronous motor 1 of the present embodiment is restarted, the modulation ratio (modulation ratio = (inverter output voltage) / (DC voltage / 2)) derived from the DC voltage detection value and the inverter output voltage calculation value is controlled to be constant with a modulation ratio target value of 0 < kH ≤ V1 / (ωKe×1.65 / 2), and control is performed to maintain the driving state (microcomputer operation state) of the permanent magnet synchronous motor 1 using the regenerative energy due to the reverse wind.

[0068] Thereby, after the permanent magnet synchronous motor 1 is started, control can be performed while balancing the reverse wind and the motor drive, and it is possible to immediately respond to overvoltage and power restoration due to a sudden increase in the reverse wind.

[0069] The present invention is not limited to the above-described embodiments, and includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0070] 1...Permanent magnet synchronous motor 2. Current detection section 3... Coordinate conversion section 4...Current control section 5…Voltage command value creation section 6…Power conversion section 7...Magnetic pole position estimation section 8...Induced voltage detector 9…Rotation speed calculation section 10…Edc detector 11…Power outage determination section 12...Current command switching means 12S1,12S2…Signal terminal 13...Rotation speed switching means 13S1,13S2…Signal terminal 14...Modulation rate control section 15…Initial startup value for power outages 16...Modulation rate calculation section 17…Modulation rate target value 18…Load 19...Outside wind 20…Fan 21...Motor 22...Motor driver IC 23...Inverter section 24...Control circuit 25…Regulator 26...Current detection section 27…Microcontroller 28…Regulator 29, 30, 31…Capacitors 100...Motor control device.

Claims

1. A motor control circuit for controlling a permanent magnet synchronous motor; A power failure detection circuit that detects a supply interruption of DC power, When the power failure detection circuit detects a power failure state, the permanent magnet synchronous motor generates power due to headwind, and when the generated energy is used to restart the permanent magnet synchronous motor, an Id current is passed as an initial value so that 0 < V1 ≦ 0.94875ωKe (V1: voltage command, ω: motor rotation speed at restart, Ke: motor power generation constant). A motor control device characterized by:

2. 2. The motor control device according to claim 1, This motor control device is characterized in that, after the permanent magnet synchronous motor is restarted, a modulation factor (modulation factor = (inverter output voltage) / (DC voltage / 2)) derived from a DC voltage detection value and an inverter output voltage calculation value is controlled to be constant at a modulation factor target value 0<kH≦V1 / (ωKe×1.65 / 2), and control is performed to maintain the permanent magnet synchronous motor in a driven state (microcomputer operating state) by using regenerative energy from headwind.

3. 2. The motor control device according to claim 1, A motor control device that detects that the power outage is occurring and that the permanent magnet synchronous motor is generating power due to headwind by calculating a theoretical value of the regenerative voltage when the power conversion unit of the motor control circuit is not being driven from an induced voltage constant and a speed detection value, and comparing the calculated theoretical value of the regenerative voltage with a DC voltage detection value.

4. 4. The motor control device according to claim 1, A motor control device that controls a fan drive motor of any one of an outdoor unit of an air conditioner, an outdoor unit of an eco-cute, a ceiling fan, and a ventilation fan.

5. A motor control method comprising the steps of: (a) detecting a current-carrying state or a power failure state of a permanent magnet synchronous motor; (b) a step of flowing an Id current as an initial value so that 0<V1≦0.94875ωKe (V1: voltage command, ω: motor rotation speed at restart, Ke: motor power generation constant) is satisfied when a power outage is detected in the step (a) and the permanent magnet synchronous motor is generating power due to headwind and the generated energy is used to restart the permanent magnet synchronous motor.

6. 6. A motor control method according to claim 5, comprising: (c) controlling a modulation factor (modulation factor=(inverter output voltage) / (DC voltage / 2)) derived from a DC voltage detection value and an inverter output voltage calculation value to be constant at a modulation factor target value 0<kH≦V1 / (ωKe×1.65 / 2); The motor control method further comprising:

7. 6. A motor control method according to claim 5, comprising: (d) calculating a theoretical value of a regenerative voltage when the power conversion unit is not driven from an induced voltage constant and a detected speed value; (e) detecting that the power outage has occurred and that the permanent magnet synchronous motor is generating power due to headwind by comparing the theoretical value of the regenerative voltage calculated in the step (d) with a detected DC voltage; The motor control method further comprising:

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