Motor drive device and semiconductor device

Abstract

To provide a motor drive device capable of implementing both noise reduction and stable activation.SOLUTION: A motor drive device 10 drives a DC motor 1 capable of detecting a mechanical angle of a rotor at every 60 degrees by three position detection elements. The motor drive device comprises: an inverter 12 of a three-phase bridge configuration which converts DC power supply input VBB into AC drive power and supplies it to the DC motor 1; and an activation control section 151 for performing drive control of the inverter 12 with a 180-degree electrification rectangular wave drive for generating an electrification section of a 120-degree electrification rectangular wave while expanding it at 60 degrees in an advance direction or generating an electrification interval of the 120-degree electrification rectangular wave while expanding it at 60 degrees in a delay direction, as an activating operation in the case of activation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor drive device that controls a brushless DC motor (hereinafter referred to as a BLDC motor). [Background technology]

[0002] There are generally several methods for starting a BLDC motor, including 120-degree energization rectangular wave starting, sine wave starting, etc. For each method, various ingenious methods are used for detecting the rotor position, switching to normal operation, etc. (See, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-306879 A Summary of the Invention [Problem to be solved by the invention]

[0004] Although the 120-degree energization rectangular wave drive can start up quickly, noise caused by the sudden changes in current that occur becomes an issue.

[0005] Sine wave startup can suppress the noise generated by 120-degree energization square wave drive, achieving quiet operation. However, since sine wave startup is an open loop control, parameters such as the duty and rotation speed at startup must be set in advance. With hardware logic, the number of parameter settings is limited, so stable startup is not possible unless the parameters are tuned according to the load. If the load is light compared to the duty and target rotation speed, the load will respond suddenly and excessively, causing noise, and if the load is heavy, the motor will step out and fail to start.

[0006] The present invention has been made in consideration of the above problems, and has an object to provide a motor drive device that can achieve both quiet operation and stable start-up. [Means for solving the problem]

[0007] The motor drive device of the present invention is a motor drive device that drives a BLDC motor capable of detecting the mechanical angle of the rotor every 60 degrees using three position detection elements, and is characterized in that it comprises a three-phase bridge-configured inverter that converts a DC power input into AC drive power and supplies it to the BLDC motor, and a start-up control unit that drives and controls the inverter with 180-degree energization rectangular wave drive, which extends the energization section of a 120-degree energization rectangular wave by 60 degrees in the leading direction or extends the energization section of a 120-degree energization rectangular wave by 60 degrees in the lagging direction as a startup operation at startup. Effect of the Invention

[0008] The motor drive device of the present invention can suppress sudden current changes at startup to achieve quiet operation, and can achieve quick and stable startup without the need to set parameters such as duty and rotation speed in advance. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing an example of the configuration of a motor drive device according to the present invention; [Diagram 2] 2 is a diagram illustrating a configuration example of an inverter illustrated in FIG. 1. [Diagram 3] 2 is a diagram showing current conduction periods during startup of the inverter shown in FIG. 1. [Figure 4] FIG. 4 is a waveform diagram showing a U-phase current at startup. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0011] 1, a motor drive device 10 of this embodiment drives a BLDC motor 1 (hereinafter referred to as a DC motor 1) based on supplied power supply and control signals. A part or all of the motor drive device 10 can be configured as a semiconductor device integrated on a substrate, and is provided in an electric device having the DC motor 1 as, for example, a semiconductor IC for driving the motor.

[0012] The DC motor 1 includes three coils 2U, 2V, and 2W for U, V, and W phases, and a rotor 3 made of a permanent magnet. The DC motor 1 includes three position detection elements 4 for detecting the position of the rotor 3. U , 4 V , 4 w The three position detection elements 4 U , 4 V , 4 w are provided at intervals of 120 degrees so that the mechanical angle of the rotor 3 can be detected at intervals of 60 degrees.

[0013] Referring to FIG. 1, the motor drive device 10 includes a power supply circuit 11, an inverter 12, a speed command determination unit 13, a position estimation unit 14, a rotation control unit 15, and a driver 16.

[0014] The power supply circuit 11 is a voltage regulator that generates an internal power supply voltage from a control circuit power supply input VCC.

[0015] As shown in FIG. 2, the inverter 12 includes upper arm switching elements Q UH , Q VH , Q WH and the lower arm switching elements Q of the U, V, and W phases. UL , Q VL , Q WL The upper arm switching element Q UH , Q VH , Q WH , lower arm switching element Q UL , Q VL , Q WLEach of these has a return current diode connected in the opposite direction. The inverter 12 converts the DC power supply input VBB into AC driving power (U-phase output U, V-phase output V, W-phase output W) and supplies the converted driving power to the DC motor 1.

[0016] The speed command determination unit 13 generates a speed command value sp from a speed command input VSP input from the outside. The rotation speed of the DC motor 1 is controlled by the speed command input VSP. The speed command determination unit 13 generates a speed command value sp that indicates the rotation speed of the DC motor 1 from the speed command input VSP within the range from the lower threshold voltage to the upper threshold voltage, and outputs the generated speed command value sp to the rotation control unit 15.

[0017] The position estimation unit 14 detects the position of the DC motor 1 using the position detection element 4 U , 4 V , 4 w Position detection element signal input H U , Position detection element signal input H V , Position detection element signal input H W Based on this, the position (mechanical angle) of the rotor 3 of the DC motor 1 is estimated, and a position estimation signal is output to the rotation control unit 15. U , 4 V , 4 w are provided at intervals of 120 degrees, so the position estimation unit 14 detects the mechanical angle of the rotor 3 at intervals of 60 degrees.

[0018] The position estimation unit 14 also receives the position detection element signal input H U , Position detection element signal input H V , Position detection element signal input H W Based on this, a rotation speed detection output FG for monitoring the rotation speed of the DC motor 1 is generated and output.

[0019] Based on the speed command value sp input from the speed command determination unit 13 and the position estimation signal input from the position estimation unit 14, the rotation control unit 15 outputs a drive control signal to the driver 16 to rotate the DC motor 1 at a rotation speed of the speed command value sp. The driver 16 generates a drive signal for driving and controlling the inverter 12, and outputs the generated drive signal to the inverter 12.

[0020] The rotation control unit 15 functions as a start-up control unit 151 that controls the inverter 12 to drive with 180-degree current rectangular wave drive as shown in FIG. 3(a) or (b) as a start-up operation at the time of start-up. At the time of start-up, the speed command value sp is input in a state in which the position estimator 14 cannot estimate the position (mechanical angle) of the rotor 3, and it is a period until the DC motor 1 reaches a preset rotation speed. FIG. 3 shows the inverter 12 upper arm switching element Q UH , Q VH , Q WH , lower arm switching element Q UL , Q VL , Q WL The respective energized sections are shown.

[0021] The 180-degree energization rectangular wave drive shown in Fig. 3(a) is an extension of the energization section of the conventional 120-degree energization rectangular wave drive shown in Fig. 3(c) by 60 degrees in the leading direction. This 180-degree energization rectangular wave drive eliminates the non-energized section, and the current waveform becomes closer to a sine wave, allowing for smooth starting and suppressing noise.

[0022] The 180-degree energization rectangular wave drive shown in Fig. 3(b) is an extension of the energization section of the conventional 120-degree energization rectangular wave drive shown in Fig. 3(c) by 60 degrees in the delay direction. This 180-degree energization rectangular wave drive also eliminates the non-energized section, and the current waveform becomes closer to a sine wave, allowing for smooth start-up and suppression of noise.

[0023] The rotation control unit 15 functions as a steady-state control unit 152 that controls the drive of the inverter 12 in a steady-state operation during a steady state after the DC motor 1 reaches a preset rotation speed. The steady-state operation by the steady-state control unit 152 is, for example, a sine wave drive.

[0024] The steady operation by the steady control unit 152 may be 120-degree current rectangular wave driving as shown in Fig. 3(c). In this case, the control logic of the start control unit 151 and the steady control unit 152 can be common, which can simplify the device and reduce costs.

[0025] Figure 4(a) shows the U-phase current waveform when 120-degree conduction square wave drive is used for startup operation. Referring to Figure 4(a), it can be seen that a steep current change occurs. When 120-degree conduction square wave drive is used for startup operation, the steep current change can cause noise problems.

[0026] Figure 4(b) shows the U-phase current waveform when sine wave PWM waveform drive is used for startup operation at startup. Referring to Figure 4(b), it can be seen that steep current changes are suppressed. However, when sine wave PWM waveform drive is used for startup operation, it is necessary to secure the initial excitation period and the forced commutation period, which may cause problems such as startup delays.

[0027] Fig. 4(c) shows the U-phase current waveform when the 180-degree conduction rectangular wave drive of this embodiment is used for the startup operation at startup. Referring to Fig. 4(c), it can be seen that when the 180-degree conduction rectangular wave drive is used for the startup operation, abrupt current changes are suppressed and startup is quick.

[0028] As described above, in this embodiment, the three position detection elements 4 U , 4 V , 4 w The motor drive device 10 drives a DC motor 1 (brushless DC motor: BLDC motor) capable of detecting the mechanical angle of the rotor every 60 degrees by a 3-phase bridge inverter 12 that converts a DC power supply input VBB into AC drive power and supplies it to the DC motor 1, and a startup control unit 151 that drives and controls the inverter 12 with 180-degree current rectangular wave drive as a startup operation at the time of startup. This configuration makes it possible to suppress sudden current changes at startup, thereby realizing quiet operation, and also to achieve rapid and stable startup without the need to set parameters such as duty and rotation speed in advance.

[0029] Furthermore, this embodiment includes a steady-state control unit 152 that controls the drive of the inverter 12 with a sinusoidal PWM waveform drive or a 120-degree conduction rectangular wave drive after a preset rotation speed is reached. When the inverter 12 is controlled to be driven using 120-degree current rectangular wave drive after reaching a preset rotation speed, the control logic of the start-up control unit 151 and the steady-state control unit 152 can be made common, thereby simplifying the device and reducing costs.

[0030] It is clear that the present invention is not limited to the above-described embodiments, and each embodiment can be appropriately modified within the scope of the technical concept of the present invention. Furthermore, the number, position, shape, etc. of the above-described components are not limited to the above-described embodiments, and the number, position, shape, etc. can be set to be suitable for implementing the present invention. The same components are denoted by the same reference numerals in each drawing. [Explanation of symbols]

[0031] 1 DC motor (brushless DC motor: BLDC motor) 3 Rotor 4 U , 4 V , 4 w Position detection element 10 Motor drive device 11 Power circuit 12 Inverter 13 Speed ​​command judgment section 14 Position estimation part 15 Rotation control section 16 Drivers 151 Start control section 152 Steady-state control section Q UH , Q VH , Q WH Upper arm switching element Q UL , Q VL , QWL Lower arm switching element

Claims

1. A motor drive device for driving a brushless DC motor capable of detecting a mechanical angle of a rotor at intervals of 60 degrees using three position detection elements, an inverter having a three-phase bridge configuration that converts a DC power supply input into AC driving power and supplies the AC driving power to the brushless DC motor; and a start-up control unit that drives and controls the inverter with 180-degree energization rectangular wave drive, which is generated by expanding the energization section of a 120-degree energization rectangular wave by 60 degrees in the leading direction or by expanding the energization section of a 120-degree energization rectangular wave by 60 degrees in the lagging direction as a start-up operation at the time of startup.

2. 2. The motor drive device according to claim 1, further comprising a steady-state control unit that drives and controls the inverter with 120-degree energization rectangular wave drive or sinusoidal PWM waveform drive after a preset rotation speed is reached.

3. 3. A semiconductor device comprising the motor drive device according to claim 1 or 2 integrated on a substrate.

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