Motor control device and motor control method

Abstract

The invention provides a motor control device which can simply and accurately identify a motor constant and a control gain required by vector control based on motor current. When the first motor driving signal VSP is conducted after the control power supply VCC is conducted, the motor constant and the control gain are identified. As an identification action, the following steps are sequentially executed: a first step of identifying armature winding resistance Ra, d-axis inductance Ld and q-axis inductance Lq; a second step for calculating a current PI control gain and a Ke estimation gain (back electromotive force estimation gain) using the identification result of the first step; a third step for calculating a counter electromotive force constant (Ke) using the identification results of the first and second steps; and a fourth step of identifying a speed PI control gain and a [theta] e estimation gain (rotor position estimation gain) using the identification result of the first step.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to a motor control device and a motor control method for numerically controlling a brushless DC (direct current) motor. BACKGROUND

[0002] A method for automatically measuring motor constants in a stationary state of a motor is disclosed (see, for example, Patent Literature 1).

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2003-164188

[0004] However, in the related art, in order to identify motor constants or control gains, a motor control device needs to be constructed using an expensive current sensor or a microcomputer. SUMMARY

[0005] The present disclosure provides a motor control device and a motor control method capable of easily and accurately identifying motor constants and control gains required for vector control based on motor currents.

[0006] The motor control device of the present disclosure controls a brushless DC motor by vector control based on detected motor currents, characterized in that the motor control device includes an identification unit that performs an identification operation of motor constants and control gains at a first motor drive signal conduction after a power supply is turned on, and as the identification operation, the identification unit sequentially performs: a first step of identifying an armature winding resistance, a d-axis inductance, and a q-axis inductance; a second step of calculating a current PI control gain and an EMF constant estimation gain using the identification results of the first step; a third step of calculating an EMF constant using the identification results of the first step and the second step; and a fourth step of identifying the speed PI control gain and a rotor position estimation gain using the identification results of the first step.

[0007] The motor control device and the motor control method of the present disclosure are capable of easily and accurately identifying motor constants and control gains required for vector control based on motor currents. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is a diagram showing the structure of an embodiment of a motor control device.

[0009] Figure 2 is a diagram showing Figure 1 the structure of a control circuit shown.

[0010] Figure 3 is a diagram illustrating the execution timing of an identification operation.

[0011] Figure 4 is a diagram showing the steps of an identification operation.

[0012] Figure 5 This is a diagram showing the motor current during operation.

[0013] Label Explanation

[0014] 2: Brushless DC motor;

[0015] 3: DC power supply;

[0016] 10: Motor control device;

[0017] 11: Inverter;

[0018] 12: Gate drive circuit;

[0019] 13: Current sensing amplifier;

[0020] 14: Regulator for control circuits;

[0021] 20: Control circuit;

[0022] 21: Three-phase dual-axis converter;

[0023] 22: Rotor position / speed estimation section;

[0024] 23: Speed ​​PI control unit;

[0025] 24: Current PI control unit;

[0026] 25: Non-interference control unit;

[0027] 26: Arithmetic unit;

[0028] 28: PWM converter section;

[0029] 27: Dual-axis three-phase converter;

[0030] 29: Motor constant / control gain identification unit. Detailed Implementation

[0031] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0032] Reference Figure 1 The motor control device 10 in this embodiment is a device for controlling the drive of the brushless DC motor 2. The motor control device 10 operates by controlling the conduction of the power supply VCC, thereby driving the brushless DC motor 2 at a speed corresponding to the motor drive signal VSP.

[0033] The motor control device 10 includes an inverter 11, a gate drive circuit 12, a current sensing amplifier 13, a regulator 14 for the control circuit, and a control circuit 20. Part or all of the motor control device 10 can be configured as a semiconductor device, i.e., a control IC, integrated on a substrate.

[0034] Inverter 11 is a three-phase inverter composed of multiple switching elements such as IGBTs. Inverter 11 has a three-phase (U-phase, V-phase, W-phase) series circuit composed of switching elements on the high-side and low-side. Inverter 11 is driven and controlled by a drive signal from the gate drive circuit 12, converting the DC voltage VDD of the DC power supply 3 into a three-phase AC voltage of a specified frequency and voltage, and outputting it to the brushless DC motor 2.

[0035] The gate drive circuit 12 outputs drive signals for each switching element of the inverter 11 based on the three-phase PWM (Pulse Width Modulation) signal supplied from the control circuit 20.

[0036] The current sensing amplifier 13 and the shunt resistors R connected in series in phases U, V, and W respectively U R V R W Together, they form a current detection circuit to detect the motor current i in phases U, V, and W. u i v i w .

[0037] The control circuit 20 uses dq vector control to process the voltage command signal applied to the brushless DC motor 2, thereby generating a three-phase PWM signal, which is then output to the gate drive circuit 12. The control circuit 20 is an information processing device such as a microcomputer that operates under program control.

[0038] Reference Figure 2 The control circuit 20, as shown in the functional block diagram, includes a three-phase dual-axis conversion unit 21, a rotor position / speed estimation unit 22, a speed PI control unit 23, a current PI control unit 24, a non-interference control unit 25, an arithmetic unit 26, a dual-axis three-phase conversion unit 27, a PWM conversion unit 28, and a motor constant / control gain identification unit 29.

[0039] The three-phase dual-axis conversion unit 21 performs a transformation from a three-phase AC coordinate system (U-phase, V-phase, W-phase) to an orthogonal dual-axis DC coordinate system (d-axis, q-axis). By performing this coordinate transformation, the three-phase dual-axis conversion unit 21 can convert the motor currents ii of the U-phase, V-phase, and W-phase inputs from the current detection amplifier 13 into a single coordinate system. u i v i w Transformed into d-axis current id and q-axis current i q The three-phase dual-axis converter 21 calculates the d-axis current i d and q-axis current i q The output is sent to the rotor position / speed estimation unit 22, the speed PI control unit 23, and the non-interference control unit 25.

[0040] The rotor position / speed estimation unit 22 is based on the d-axis current i calculated by the three-phase dual-axis conversion unit 21. d and q-axis current i q The rotor position θ is estimated. e and actual speed ω e The rotor position / speed estimation unit 22 estimates the rotor position θ. e The output is sent to the three-phase dual-axis converter 21, and the estimated actual speed ω is transmitted. e The output is sent to the speed PI control unit 23 and the non-interference control unit 25.

[0041] Speed ​​PI control unit 23 controls the speed command value ω e * With actual speed ω e The deviation is used as the input for PI control to calculate the d-axis current command value i. d * and q-axis current command value i q * They are then output to the current PI control unit 24.

[0042] The current PI control unit 24 controls the d-axis current command value i d * and q-axis current command value i q * With d-axis current i d and q-axis current i q The deviation is used as the input for PI control to calculate the d-axis voltage V. d and q-axis voltage V q They are then output to the arithmetic unit 26.

[0043] The non-interference control unit 25 will control the speed ω e d-axis current i d q-axis current i q As input, the non-interference voltage required to cancel the interference voltage between the d-axis and q-axis is calculated and output to the arithmetic unit 26.

[0044] The arithmetic unit 26 calculates the d-axis voltage V by the current PI control unit 24. d and q-axis voltage V qThe non-interference voltage calculated by the non-interference control unit 25 is added (offset) and input to the biaxial three-phase conversion unit 27.

[0045] The dual-axis three-phase conversion unit 27 performs a transformation from an orthogonal dual-axis DC coordinate system (d-axis, q-axis) to a three-phase AC coordinate system (U-phase, V-phase, W-phase). By performing this coordinate transformation, the dual-axis three-phase conversion unit 27 can convert the d-axis voltage V input from the arithmetic unit 26 into a three-phase AC coordinate system. d and q-axis voltage V q Transformed into phase voltage V u V v V w .

[0046] The PWM converter 28 converts the phase voltage V u V v V w The signal is compared with a carrier wave (triangular wave, sawtooth wave, etc.) to generate a PWM signal with a specified duty cycle.

[0047] Reference Figure 3 When the control power supply VCC is turned on (step S101) and the first motor drive signal VSP is turned on (step S102), the motor constant / control gain identification unit 29 performs the identification operation of motor constant and control gain (step S103). The motor constant / control gain identification unit 29 sets the motor constant and control gain identified in step S103 as the control parameters of the rotor position / speed estimation unit 22, speed PI control unit 23, current PI control unit 24, and non-interference control unit 25.

[0048] Therefore, the brushless DC motor 2 performs sensorless vector control appropriately based on the motor constant and control gain identified in step S103, and starts motor drive (step S104).

[0049] Even if the motor drive signal VSP is disconnected (step S105) while the control power supply VCC remains on, the states of the motor constant and control gain identified in step S103 will be maintained. Therefore, if the motor drive signal VSP is turned on again (step S106), step S104 is reached and motor driving begins.

[0050] When the control power supply VCC is disconnected (step S105), the control parameters of the rotor position / speed estimation unit 22, speed PI control unit 23, current PI control unit 24 and non-interference control unit 25 are initialized (the motor constant and control gain identified in step S103 are eliminated), and the operation from step S101 is restarted.

[0051] The digital control execution of control circuit 20 combines sensorless vector control with algorithms for rotor position estimation and vector control. The control parameters required to implement the rotor position estimation and vector control algorithms are determined based on motor constants.

[0052] The motor constant / control gain identification unit 29 identifies the armature winding resistance "Ra", d-axis inductance "Ld", q-axis inductance "Lq", and back EMF constant "Ke" as motor constants. In the rotor position estimation algorithm of the rotor position / speed estimation unit 22, the position estimation observer uses "Ra", "Ld", and "Lq", and the back EMF estimation observer uses "Ra", "Ld", "Lq", and "Ke". Furthermore, in the vector control algorithm, the current PI control unit 24 uses "Ld", "Lq", and "Ra", the speed PI control unit 23 uses "Ke" and "Lq", and the non-interference control unit 25 uses "Ra", "Ld", "Lq", and "Ke".

[0053] Motor constant / control gain identification unit 29 identifies the current PI control gain in current PI control unit 24, the speed PI control gain in speed PI control unit 23, the Ke estimated gain in rotor position / speed estimation unit 22, and θ. e The estimated gain is used as the control gain.

[0054] like Figure 4 as well as Figure 5 As shown, the motor constant / control gain identification unit 29 identifies the motor constant and control gain by sequentially executing the first to fourth steps. Figure 5 The identification of motor constants and control gain is shown, along with the execution timing and motor current i. u i v i w The relationship.

[0055] In the first step, the measurements of “Ra”, “Ld” and “Lq” of the motor constants to be identified are performed sequentially.

[0056] The measurement of "Ra" is: detecting the motor current i when the switching element on the high side of one phase (e.g., phase U) is turned on to the switching element on the low side of the other two phases (e.g., phases V and W). u i v i w In the motor current i u When the value is I, the motor current i v i w The value is -I / 2. Using the measured I and VDD, calculate "Ra" based on (2 / 3)×VDD / I.

[0057] The measurement of "Ld" is as follows: the switching element on the high side of one phase (e.g., phase U) is turned on with the switching elements on the low side of the other two phases (e.g., phases V and W), and the time constant t is measured. "Ld" is calculated using the measured t and "Ra" and based on t × "Ra".

[0058] The measurement of "Lq" is as follows: an AC voltage of frequency f is applied to two phases of the three-phase system (e.g., phase V and phase W), and the applied voltage V is measured. v Amplitude, motor current i v The amplitude and phase difference θ. Using the detected V v i v , θ and f as existing values, according to (V v ×sinθ) / (i v We can calculate "Lq" using the formula (×2πf).

[0059] In the second step, the current PI control gain and the estimated Ke gain are set. The current PI control gain and the estimated Ke gain are calculated based on the values ​​of Ra, Ld, and Lq identified in the first step.

[0060] In the third step, the estimation of "Ke" within the motor constant to be identified is performed. The current and voltage values ​​are detected when the brushless DC motor 2 is rotated at a constant speed ω using open-loop control. The detected current and voltage values, the calculated values, and the existing values ​​are used to estimate the back electromotive force e. q And according to e q / ω is used to calculate "Ke".

[0061] In the fourth step, the speed PI control gain and the estimated gain θe are set. The speed PI control gain and the estimated gain θe are calculated based on the values ​​of "Ra", "Ld", and "Lq" identified in the first step.

[0062] As explained above, this implementation method is based on the detected motor current i u i v i wThe motor control device 10, which uses vector control to control the brushless DC motor 2, includes a motor constant / control gain identification unit 29 (identification unit). When the first motor drive signal VSP is activated after the control power supply VCC is turned on, the motor constant / control gain identification unit 29 performs identification operations on the motor constant and control gain. As an identification operation, the motor constant / control gain identification unit 29 sequentially performs the following steps: First step, identifying the armature winding resistance "Ra", the d-axis inductance "Ld", and the q-axis inductance "Lq"; Second step, using the identification results of the first step, calculating the current PI control gain and the estimated gain Ke (back electromotive force estimated gain); Third step, using the identification results of the first and second steps, calculating the back electromotive force constant "Ke"; and Fourth step, using the identification results of the first step, identifying the speed PI control gain and the estimated gain θe (rotor position estimated gain). According to this structure, it is possible to easily and accurately identify the motor constant based on the motor current i u i v i w The motor constants and control gain required for vector control.

[0063] Furthermore, according to this embodiment, even if the motor drive signal VSP is disconnected while the control power supply VCC is continuously on, the motor constant and control gain identified by the motor constant / control gain identification unit 29 are maintained, and are eliminated when the control power supply VCC is disconnected. With this structure, appropriate identification of the motor constant and control gain can be performed at appropriate timing.

[0064] Furthermore, the present invention is not limited to the embodiments described above, and obviously, within the scope of the technical concept of the present invention, the embodiments can be appropriately modified. In addition, the number, position, shape, etc., of the above-described constituent components are not limited to the embodiments described above, and appropriate numbers, positions, shapes, etc., can be provided for implementing the present invention. Furthermore, in each figure, the same reference numerals are used to label the same constituent element.

Claims

1. A motor control device that controls a brushless DC motor by vector control based on detected motor current, characterized in that, The motor control device includes an identification unit that performs an identification operation on the motor constant and control gain when the motor drive signal is first turned on after the control power is turned on. As part of the identification action, the identification unit executes the following sequentially: The first step is to identify the armature winding resistance, d-axis inductance, and q-axis inductance. The second step is to use the identification results from the first step to calculate the current PI control gain and the estimated gain of the back electromotive force constant. The third step is to calculate the back electromotive force constant using the identification results from the first and second steps. as well as The fourth step is to use the identification results from the first step to identify the speed PI control gain and the rotor position estimation gain.

2. The motor control device according to claim 1, characterized in that, When the control power supply is continuously on, even if the motor drive signal is disconnected, the motor constant and the control gain identified by the identification unit are maintained, and the motor constant and the control gain identified by the identification unit are eliminated when the control power supply is disconnected.

3. A motor control method, which controls a brushless DC motor by vector control based on detected motor current, characterized in that, When the motor drive signal VSP is turned on for the first time after the control power is turned on, the motor constant and control gain identification action is performed. The identification actions are performed sequentially: The first step is to identify the armature winding resistance, d-axis inductance, and q-axis inductance as the motor constants. The second step is to use the identification results from the first step to calculate the current PI control gain and the back electromotive force estimated gain. The third step is to calculate the back electromotive force constant using the identification results from the first and second steps. as well as The fourth step is to use the identification results from the first step to identify the speed PI control gain and the rotor position estimation gain.

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