Motor control device, motor control method, and semiconductor device

Abstract

To provide a motor control device and a motor control method that can suppress a current change at a rotation stopping operation.SOLUTION: A motor control device comprises: a speed command voltage determination unit 53 that determines a speed command voltage value Vsp' equal to or higher than a driving start threshold voltage value Vth in multiple steps, and outputs a determination result as a speed command value SP; an advance value calculation unit 54; and a rotation control unit 56 that generates a control signal that reflects the speed command value SP for each predetermined reflection time and reflects an advance value AA at each rotation of a mechanical angle of a DC brushless motor 10. When the speed command value SP is less than the driving start threshold voltage value Vth, the speed command voltage determination unit 53 gradually reduces the speed command value SP at each reflection time as a rotation stopping operation, and the advance value calculation unit 54 gradually reduces the advance value AA at each reflection time in conjunction with the speed command value SP. The rotational control unit 56 generates a control signal which reflects the speed command value SP and the advance value AA at each reflection time.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a motor control device and a motor control method for controlling an IPM motor.

Background Art

[0002] Conventionally, as a DC brushless motor used in devices such as an air conditioner fan motor, a surface magnet type SPM (Surface Permanent Magnet) motor in which a permanent magnet such as ferrite is arranged on the surface of a rotor has been adopted. In recent years, for the main purpose of cost reduction, a model change has been implemented from an SPM motor to an IPM (Interior Permanent Magnet) motor. As shown in Patent Document 1, an IPM motor is a motor having a structure in which a permanent magnet is embedded in a rotor portion, such as a spoke motor in which magnets are arranged radially.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the IPM motor has a stronger or weaker rotating magnet than the SPM motor, when the current is rapidly changed during startup or steady-state stop, a rattling sound is generated due to unstable torque fluctuations. In particular, in the stop control of a fan motor or the like, since the motor control device is designed to abruptly cut off the drive of the inverter when a stop signal is detected, the change in current is drastic and the rattling sound has become a problem.

[0005] The present disclosure lies in providing a motor control device and a motor control method capable of suppressing a change in current during a rotation stop operation.

Means for Solving the Problems

[0006] The motor control device of the present disclosure is a motor control device that generates a control signal for driving a motor having a structure in which permanent magnets are embedded in a rotor portion, and includes a VSP terminal to which a speed command voltage is input, and the speed command voltage equal to or higher than a drive start threshold voltage is determined in multiple stages, and a speed command determination unit that outputs a determination result as a speed command value, an electrical angle value calculation unit that calculates an electrical angle value based on both or either of the speed command value and an electrical angle command input from the outside, and a rotation control unit that generates the control signal in which the electrical angle value is reflected every mechanical angle rotation of the motor and the speed command value is reflected every predetermined reflection time set in advance. When the speed command voltage is less than the drive start threshold voltage, as a rotation stop operation, the speed command determination unit gradually decreases the speed command value every reflection time, the electrical angle value calculation unit gradually decreases the electrical angle value every reflection time in conjunction with the speed command value, and the rotation control unit generates the control signal in which the speed command value and the electrical angle value are reflected every reflection time. Further, the motor control method according to the present invention is a motor control method for generating a control signal for driving a motor having a structure in which permanent magnets are embedded in a rotor portion. The controller that generates the control signal receives an input of a speed command voltage, determines the speed command voltage equal to or higher than a drive start threshold voltage in multiple stages, and sets the determination result as a speed command value, calculates an electrical angle value based on both or either of the speed command value and an electrical angle command input from the outside, and generates the control signal in which the electrical angle value is reflected every mechanical angle rotation of the motor and the speed command value is reflected every predetermined reflection time set in advance. When the speed command voltage is less than the drive start threshold voltage, as a rotation stop operation, the speed command value is gradually decreased every reflection time, the electrical angle value is gradually decreased every reflection time in conjunction with the speed command value, and the control signal in which the speed command value and the electrical angle value are reflected every reflection time is generated.

Advantages of the Invention

[0007] The motor control device disclosed herein can suppress abrupt current changes and prevent noise from the DC brushless motor by gradually lowering the speed command value at each reflection time as a rotation stopping operation. Also, by gradually lowering the lead angle value in conjunction with the speed command value, it is possible to eliminate deviations in the lead angle value and realize a rotation stopping operation while performing optimal control. [Brief description of the drawings]

[0008]

Figure 1

Figure 2

[0009] A DC brushless motor 10 driven by motor control device 1 of the present embodiment is an IPM (Interior Permanent Magnet) motor, such as a spoke motor, having a structure in which a permanent magnet is embedded in the rotor portion.

[0010] Referring to FIG. 1, the motor control device 1 includes an inverter circuit 2, a high-side driver 3 and a low-side driver 4 which are drive circuits, and a controller 5.

[0011] The high-side driver 3, the low-side driver 4, and the controller 5 can be configured as a semiconductor integrated circuit integrated on a semiconductor substrate and sealed in a resin package to form a semiconductor device. The high-side driver 3, the low-side driver 4, and the controller 5 may be the same semiconductor device or may be separate semiconductor devices. Furthermore, the inverter circuit 2 may be built into the same resin package.

[0012] The motor control device 1 includes a VBB terminal to which the motor power supply voltage VBB is connected, an LS terminal and a COM terminal to which a common line is connected, a U-phase output terminal U, a V-phase output terminal V, and a W-phase output terminal W. The motor control device 1 includes a VSP terminal to which a speed command voltage VSP is input, an LA terminal to which an advance angle command voltage LA is input, and an IS terminal to which a calculation method instruction voltage IS is input.

[0013] The DC brushless motor 10 includes a hall element (not shown) that detects the position of the rotor and outputs a rotor position detection signal. The motor control device 1 includes a U-phase hall element signal input terminal HUP, HUN, a V-phase hall element signal input terminal HVP, HVN, and a W-phase hall element signal input terminal HWP, HWN to which the rotor position detection signal from the DC brushless motor 10 is input.

[0014] The inverter circuit 2 includes a half-bridge circuit for the U-phase, a half-bridge circuit for the V-phase, and a half-bridge circuit for the W-phase. Each of the half-bridge circuits includes a high-side switching element QH and a low-side switching element QL connected in series between the VBB terminal and the LS terminal. The inverter circuit 2 outputs the motor power supply voltage VBB as AC driving power from the U-phase output terminal U, the V-phase output terminal V, and the W-phase output terminal W to drive the DC brushless motor 10.

[0015] The high-side switching element QH and the low-side switching element QL are composed of, for example, a metal oxide semiconductor field effect transistor (MOSFET: Metal-Oxide-Semiconductor Field Effect Transistor). The high-side switching element QH and the low-side switching element QL may also be other switching devices such as an insulated gate bipolar transistor (IGBT: Insulated Gate Bipolar Transistor).

[0016] The high-side driver 3 includes a control power input terminal Vcc1 for inputting a control power supply voltage Vcc, and a control ground terminal COM1 connected to the common line. The high-side driver 3 includes high-side control signal input terminals HIN1 to HIN3 and high-side drive signal output terminals HO1 to HO3. Based on the high-side control signals from the controller 5 input to the high-side control signal input terminals HIN1 to 3, the high-side driver 3 generates a high-side drive signal for turning on and off the high-side switching element QH of the inverter circuit 2 and outputs it from the high-side drive signal output terminals HO1 to HO3.

[0017] The low-side driver 4 includes a control power input terminal Vcc2 for inputting a control power supply voltage Vcc, and a control ground terminal COM2 connected to the common line. The low-side driver 4 includes low-side control signal input terminals LIN1 to LIN3 and low-side drive signal output terminals LO1 to LO3. Based on the low-side control signals from the controller 5 input to the low-side control signal input terminals LIN1 to 3, the low-side driver 4 generates a low-side drive signal for turning on and off the low-side switching element QL of the inverter circuit 2 and outputs it from the low-side drive signal output terminals LO1 to LO3.

[0018] The controller 5 includes a control power input terminal Vcc3 for inputting a control power supply voltage Vcc, and a control ground terminal COM3 connected to the common line. The controller 5 includes ADCs (analog-to-digital conversion circuits) 52a to 52c, a speed command determination unit 53, an advance angle value calculation unit 54, a position estimation unit 55, and a rotation control unit 56.

[0019] The rotational speed of the DC brushless motor 10 is controlled by the speed command voltage VSP input to the VSP terminal. The speed command voltage VSP is input to the ADC 52a, converted into a speed command voltage value VSP', and input to the speed command determination unit 53 and the advance angle value calculation unit 54.

[0020] When the speed command voltage value VSP’ is equal to or higher than a preset drive start threshold voltage value Vth, the speed command determination unit 53 generates a speed command value SP for instructing the rotational speed of the DC brushless motor 10 and outputs it to the rotation control unit 56. The speed command determination unit 53 determines the speed command voltage value VSP’ that is equal to or higher than the drive start threshold voltage value Vth in multiple steps (for example, 508 steps), and outputs the determination result as the speed command value SP.

[0021] The advance angle value of the DC brushless motor 10 is determined according to the advance angle command voltage LA input to the LA terminal and the calculation method instruction voltage IS input to the IS terminal. The advance angle command voltage LA is input to the ADC52b, converted into an advance angle command voltage value LA’, and input to the advance angle value calculation unit 54. The calculation method instruction voltage IS is input to the ADC52c, converted into a calculation method instruction voltage value IS’, and input to the advance angle value calculation unit 54.

[0022] The advance angle value calculation unit 54 calculates an advance angle value AA using both or either of the speed command voltage value VSP’ and the advance angle command voltage value LA’ according to the calculation method indicated by the calculation method instruction voltage value IS’, and outputs it to the rotation control unit 56.

[0023] The position estimation unit 55 includes a U-phase hall element signal input terminal HUP, HUN, a V-phase hall element signal input terminal HVP, HVN, and a W-phase hall element signal input terminal HWP, HWN. Based on the rotor position detection signals input to these input terminals, the position estimation unit 55 generates a rotation speed detection output FG for monitoring the rotation speed of the DC brushless motor 10 and outputs it to the rotation control unit 56.

[0024] The rotation control unit 56 generates a high-side control signal and a low-side control signal for rotating the DC brushless motor 10 at the rotation speed of the speed command value SP and the advance angle value AA based on the speed command value SP input from the speed command determination unit 53, the advance angle value AA input from the advance angle value calculation unit 54, and the rotation speed detection output FG input from the position estimation unit 55, and outputs them to the high-side driver 3 and the low-side driver 4 respectively. The speed command value SP is reflected in the high-side control signal and the low-side control signal every predetermined time (for example, 50 μs), and the advance angle value AA is reflected in the high-side control signal and the low-side control signal every one rotation of the mechanical angle of the DC brushless motor 10.

[0025] When the speed command voltage VSP input to the VSP terminal reaches the motor rotation stop level set and the speed command voltage value VSP' is less than the drive start threshold voltage value Vth, the speed command determination unit 53 executes a rotation stop operation to stop the rotation of the DC brushless motor 10. Fig. 2(a) is a sequence diagram of the rotation stop operation when the speed command value SP at the start of the rotation stop operation is 508 in digital value conversion. Fig. 2(b) is a sequence diagram of the rotation stop operation when the speed command value SP at the start of the rotation stop operation is 256 in digital value conversion. Although shown in digital values in the figure, analog values without steps may also be used.

[0026] In the rotation stop operation, the speed command determination unit 53 does not immediately set the output speed command value SP to zero, but gradually decreases the level of the output speed command value SP to reach zero as shown in Fig. 2. In the rotation stop operation, the speed command determination unit 53 decreases the speed command value SP every predetermined time (hereinafter referred to as the reflection time) reflected in the high-side control signal and the low-side control signal. Thereby, sudden current changes are suppressed, and the noise of the DC brushless motor 10 is suppressed.

[0027] In the rotation stop operation, the speed command determination unit 53 changes the slope of the decrease according to the speed command value SP. When the level of the speed command value SP exceeds a preset speed threshold, the speed command determination unit 53 relaxes the slope of decreasing the speed command value SP. When the speed command value SP is equal to or less than the preset speed threshold, the speed command determination unit 53 sharpens the slope of decreasing the speed command value SP. In the example shown in FIG. 2, the speed threshold is set to 256 in digital value conversion. When the speed command value SP exceeds 256 in digital value conversion, the speed command determination unit 53 decreases the speed command value SP by 8 steps in digital value conversion. When the speed command value SP is 256 or less in digital value conversion, the speed command determination unit 53 decreases the speed command value SP by 16 steps in digital value conversion.

[0028] If the slope of decrease is to be made gentle or sharp according to the magnitude of the speed command value SP, two or more speed thresholds may be set, and the slope of decreasing the speed command value SP may be changed in three or more ways. Also, a function or table for determining the slope of decrease according to the speed command value SP may be set.

[0029] When the speed command voltage VSP input to the VSP terminal reaches the set motor rotation stop level and the speed command voltage value VSP' becomes less than the drive start threshold voltage value Vth, the advance angle value calculation unit 54 executes a rotation stop operation for stopping the rotation of the DC brushless motor 10 together with the speed command determination unit 53. In the rotation stop operation, as shown in FIG. 2, the advance angle value calculation unit 54 gradually decreases the advance angle value AA in conjunction with the speed command value SP decreased by the speed command determination unit 53 for each reflection time. That is, the speed command determination unit 53 and the advance angle value calculation unit 54 link the update of the speed command value SP and the update of the advance angle value AA. The advance angle value AA may be calculated using a function or table determined according to the speed command value SP, or may be decreased by a preset predetermined angle. Thereby, the deviation of the advance angle value AA can be eliminated, and the rotation stop operation can be realized while performing optimal control.

[0030] As described above, this embodiment relates to a motor control device 1 that generates control signals (high-side control signal and low-side control signal) for driving a DC brushless motor 10 having a structure in which a permanent magnet is embedded in a rotor portion, and includes a VSP terminal to which a speed command voltage Vsp is input, a speed command determination unit 53 that determines a speed command voltage value Vsp′ that is equal to or greater than a drive start threshold voltage value Vth in multiple stages and outputs the determination result as a speed command value SP, and a lead-angle value calculation unit 54 that calculates a lead-angle value AA based on the speed command value SP and / or a lead-angle command voltage LA input from the outside. 4, and a rotation control unit 56 that generates a control signal that reflects the speed command value SP for each preset reflection time, and the lead-angle value AA for each mechanical rotation of the DC brushless motor 10, and when the speed command voltage Vsp becomes less than the drive start threshold voltage value Vth, as a rotation stopping operation, the speed command determination unit 53 gradually lowers the speed command value SP for each reflection time, and the lead-angle value calculation unit 54 gradually lowers the lead-angle value AA for each reflection time in conjunction with the speed command value SP, and the rotation control unit 56 generates a control signal that reflects the speed command value SP and the lead-angle value AA for each reflection time. With this configuration, by gradually lowering the speed command value SP for each reflection time as a rotation stopping operation, it is possible to suppress abrupt current changes and prevent noise from the DC brushless motor 10. Also, by gradually lowering the lead-angle value AA in conjunction with the speed command value SP, it is possible to eliminate deviations in the lead-angle value AA and achieve a rotation stopping operation while performing optimal control.

[0031] Furthermore, in this embodiment, the speed command determination unit 53 accelerates or decreases the rate at which the speed command value SP is decreased depending on the magnitude of the speed command value SP. This configuration makes it possible to suppress abrupt changes in current and to stop the rotation of DC brushless motor 10 quickly and smoothly.

[0032] Note that the present invention is not limited to the above-described embodiments, and it is obvious that each embodiment can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, position, shape, etc. of the above-described constituent members are not limited to the above-described embodiments, and can be set to appropriate numbers, positions, shapes, etc. for implementing the present invention. The same reference numerals are given to the same components in each figure.

Explanation of Reference Numerals

[0033] 1 Motor control device 2 Inverter circuit 3 High-side driver 4 Low-side driver 5 Controller 10 DC brushless motor 52a, 52b, 52c ADC (Analog-to-Digital Conversion Circuit) 53 Speed command determination unit 54 Advance angle value calculation unit 55 Position estimation unit 56 Rotation control unit

Claims

1. A motor control device that generates a control signal for driving a motor having a structure in which permanent magnets are embedded in a rotor portion, a VSP terminal to which a speed command voltage is input, a speed command determination unit that determines the speed command voltage equal to or higher than a drive start threshold voltage in multiple stages and outputs the determination result as a speed command value, an advance angle value calculation unit that calculates an advance angle value based on both or either of the speed command value and an advance angle command input from the outside, a rotation control unit that generates the control signal in which the advance angle value is reflected every predetermined reflection time of the speed command value and the advance angle value is reflected every one rotation of the mechanical angle of the motor, and is provided with, when the speed command voltage becomes less than the drive start threshold voltage, as a rotation stop operation, the speed command determination unit gradually decreases the speed command value every reflection time, and the advance angle value calculation unit gradually decreases the advance angle value every reflection time in conjunction with the speed command value, and the rotation control unit generates the control signal in which the speed command value and the advance angle value are reflected every reflection time. A motor control device characterized by the above.

2. The motor control device according to claim 1, wherein the speed command determination unit adjusts the slope of decreasing the speed command value according to the magnitude of the speed command value.

3. A motor control method for generating a control signal for driving a motor having a structure in which permanent magnets are embedded in a rotor portion, the controller that generates the control signal, receives an input of a speed command voltage, determines the speed command voltage equal to or higher than a drive start threshold voltage in multiple stages and sets the determination result as a speed command value, calculates an advance angle value based on both or either of the speed command value and an advance angle command input from the outside, generates the control signal in which the advance angle value is reflected every predetermined reflection time of the speed command value and the advance angle value is reflected every one rotation of the mechanical angle of the motor, when the speed command voltage becomes less than the drive start threshold voltage, as a rotation stop operation, the speed command value is gradually decreased every reflection time, and the advance angle value is gradually decreased every reflection time in conjunction with the speed command value, and the control signal in which the speed command value and the advance angle value are reflected every reflection time is generated. A motor control method characterized by the above.

4. A semiconductor device characterized in that the motor control device according to claim 1 or 2 is provided.

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