JP2009254184A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller preferable to suppress the fluctuation of an AC output to a brushless motor generated by the effect of the voltage fluctuation of an AC power supply. <P>SOLUTION: The motor controller contains an AC-power supply section 10 including first and second supply lines and having a configuration connecting the second supply line to a frame ground, a full-wave rectifier 11 and a smoothing circuit 12 having the configuration connecting first and second smoothing capacitors C1 and C2 in series while electrically connecting the connecting sections of the first and second smoothing capacitors to the second supply line and smoothing a rectifying input and generating a DC output. The motor controller further contains an inverter circuit 13 converting the DC output into an AC output by the switching operations of Tr1 to Tr6 and supplying each armature winding for the brushless motor 200 with the AC output and a control circuit 15 generating a control signal controlling the operation of the inverter circuit 13 on the basis of a command signal and supplying the inverter circuit 13 with the control signal. The motor controller further contains a microcomputer 16 generating the command signal on the basis of a positional signal from a Hall element and supplying the control circuit 15 with the command signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a brushless motor control device including a full-wave rectifier circuit, a smoothing circuit, and an inverter circuit, and more particularly, generated by a switching operation of a switching element constituting the inverter circuit when positioning of the brushless motor is completed. The present invention relates to a motor control device suitable for suppressing vibration.

Conventionally, for example, there is a motor control device that rectifies and smoothes an input from an AC power source to obtain a DC output, converts the DC output into an AC output in an inverter circuit, and supplies the AC output to a brushless motor (for example, Patent Document 1). See).
Hereinafter, based on FIG. 4, the structure of the conventional motor control apparatus is demonstrated.
Here, FIG. 4 is a circuit diagram showing a configuration of a conventional motor control device. FIG. 5 is a diagram showing how the DC link voltage is divided. FIG. 6 is a diagram illustrating a current path when the power supply voltage is equal to or lower than the output voltage of the inverter. FIG. 7 is a diagram showing a current path when the power supply voltage becomes larger than the output voltage of the inverter.

As shown in FIG. 4, the conventional motor control device is configured to include four components, that is, an AC power source, a rectifying unit, a smoothing unit, and an inverter unit.
The AC power source is an AC 200 V power source having a configuration in which two AC 100 [V] AC power sources are connected in series and the connection portion is connected to a frame ground (hereinafter referred to as FG). It is connected to the rectifier. The rectifying unit includes four diodes connected in a bridge, and performs full-wave rectification on an AC input from an AC power supply and outputs the rectified output. The smoothing unit is configured to include one smoothing capacitor, and smoothes the full-wave rectified output from the rectifying unit to generate a DC output. Further, a capacitor (hereinafter referred to as C_NFG) having a function of suppressing noise from the power supply line is connected between the DC link reference point N and FG on the negative side of the smoothing capacitor (between N and FG). ing. The N-FG voltage (hereinafter referred to as v_NFG) is generated by the charging of C_NFG.

  The inverter unit is configured to include three half-bridge circuits in which two transistors such as IGBTs (Insulated Gate Bipolar Transistors) are connected in series, and the DC output of the smoothing unit is converted to AC output by switching the transistors. And supplied to each winding constituting the U phase, V phase, and W phase of the three-phase brushless motor to be controlled. Further, the brushless motor is driven at a variable speed by controlling the switching operation of the transistors constituting each half bridge circuit by a PWM signal from a control unit (not shown). In the example of FIG. 4, the output of the inverter unit (connection portion of each two transistors) is electrically connected to the windings of each phase of the three-phase brushless motor via an electric cable.

  In the motor control device having the above configuration, a stray capacitance (stray capacitor) Cs is generated between the electric cable and the FG, so that a current flows to each component via the stray capacitance Cs. However, the AC power supply voltage (v1, v2) with respect to the FG and the voltage (v_OFG) between the connection portions O and FG (between O-FG) of each of the two transistors of the inverter unit serving as an output unit of AC power. The path through which the current flows changes depending on the magnitude relationship.

First, (a) the current path when the absolute values of v1 and v2 are equal to or smaller than the absolute value of v_OFG (| v1 |, | v2 | ≦ | v_OFG |) will be described.
In this case, for example, when the positioning of the brushless motor is completed, when the high-side transistor of each half-bridge circuit of the inverter is switched, as shown in FIG. 5, the capacitor C_NFG and the floating capacitance Cs The DC link voltage corresponding to the capacitance is divided between O and FG. On the other hand, when the transistor on the low side of each half-bridge circuit is switched, a loop is formed via the capacitor C_NFG and the floating capacitance Cs. In addition, P in FIG. 4 is a DC link point on the positive electrode side of the smoothing capacitor. Further, when the smoothing capacitor is charged, the voltage between PN becomes about 282 [V].

Specifically, when | v1 | and | v2 | are equal to or smaller than | v_OFG |, the path of the current that flows when the high side switches is as shown in FIG. 6 is “P → O → Cs → FG → C_NFG → N (solid line) ”. Further, the path of the current that flows when the low side is switched is “N → C_NFG → FG → Cs → O → N (dashed line)”.
Next, the current path when (b) the absolute values of v1 and v2 are larger than the absolute value of v_OFG (| v1 |, | v2 |> | v_OFG |) will be described.

In this case, since v1 and v2 exceed the divided voltage of the DC link voltage applied to the floating capacitance Cs, the diode of the rectifier is biased forward and turned on. As a result, the voltages at points P and N with respect to FG become the same potential as v1 and v2 with respect to FG.
Therefore, for example, when the positioning of the brushless motor is completed, the path of the current that flows when the high-side transistor of each half-bridge circuit of the inverter unit is switched is represented by “P → O → Cs → FG → C_NFG → N (thin solid line) ”and“ P → O → Cs → FG → v1, v2 → rectifier diode → P (one-dot chain line) ”.

On the other hand, as shown in FIG. 7, the path of the current that flows when the low-side transistor of each half-bridge circuit of the inverter unit is switched is “N → C_NFG → FG → Cs → O → N (solid line (bold)). And “N → rectifier diode → v1, v2 → FG → Cs → O → N (dotted line)”.
Japanese Patent Laid-Open No. 09-074790

  However, in the above prior art, for example, when the absolute value of v1 and v2 becomes larger than the absolute value of v_OFG due to the switching operation of the switching elements constituting the inverter circuit at the completion of positioning of the motor, as described above. In addition, a current path passing through the AC power source is formed, and the voltages at the P point and the N point with respect to the FG become the same potential as v1 and v2 with respect to the FG. Therefore, as shown in FIG. 8, the voltage between P-FG and the voltage between N-FG fluctuate with the fluctuation of AC voltages v1 and v2 in the period when the absolute values of v1 and v2 are larger than the absolute value of v_OFG. The shape becomes a mountain every half cycle of the power cycle. Here, FIG. 8 shows waveforms of the AC power supply (v1, v2), v_OFG, and v_NFG when the switching elements of the inverter circuit in the motor control device having the conventional configuration are simultaneously switched at the duty ratio of 50 [%]. It is a figure which shows the relationship. In FIG. 8, the horizontal axis represents time [ms], and the vertical axis represents voltage [V]. Since a current similar to a mountain-like variation of v_OFG shown in FIG. 8 flows through the winding of the brushless motor, a slight vibration is generated in the motor position deviation, which may hinder high-precision positioning.

  Therefore, the present invention has been made paying attention to such an unsolved problem of the conventional technology, and suppresses the fluctuation of the AC output to the brushless motor caused by the influence of the voltage fluctuation of the AC power supply. An object of the present invention is to provide a suitable motor control device.

  [Invention 1] In order to achieve the above object, a motor control device of Invention 1 is a motor control device that controls the operation of a brushless motor, and has two supply lines for supplying AC power, Including two sets of AC power supply means configured such that one of the supply lines is electrically connected to the frame ground and two diodes connected in series in the forward direction, and the two sets of anode-side terminals And the cathode side terminals are electrically connected to each other to form a diode bridge circuit, and one of the two sets is electrically connected to the one supply line, and the other is connected in series. A full-wave rectification circuit configured to full-wave rectify the AC input from the AC power supply means by the diode bridge circuit, a first smoothing capacitor, 2 Including a smoothing capacitor, wherein one terminal of the first smoothing capacitor is electrically connected to the cathode side connection of the diode bridge circuit, and one terminal of the second smoothing capacitor is connected to the anode side Electrically connecting the other terminals of the first and second smoothing capacitors, electrically connecting the connecting part to the one supply line, and connecting the first and second smoothing capacitors. A smoothing circuit configured to smooth the rectified input from the full-wave rectifier circuit and boost the voltage to a double voltage by a smoothing capacitor of 2 and a plurality of switching elements, and from the one terminal of the first smoothing capacitor The first DC output and the second DC output from the one terminal of the second smoothing capacitor are supplied to the brushless motor through the switching element, and An inverter circuit configured to perform switching operation of a plurality of switching elements to alternately switch the first DC output and the second DC output to the brushless motor, and a position for detecting a rotational position of the brushless motor Control means for generating a control signal for controlling the switching operation of the inverter circuit based on the rotational position detected by the detection means, and supplying the control signal to the switching element.

  With such a configuration, for example, one of the two supply lines such as a Japanese commercial power supply is frame grounded, and the one supply line of the AC power supply is electrically connected to one supply line of the AC power supply means. Are connected to each other and the other supply lines are electrically connected to each other, so that AC power is supplied to the full-wave rectifier circuit via a supply line of the AC power supply means. As a result, the AC power is full-wave rectified in the full-wave rectifier circuit and output to the smoothing circuit. In the smoothing circuit, the first smoothing capacitor and the second smoothing capacitor smooth the rectified input from the full-wave rectifier circuit to generate a DC output. At this time, the connection portion of the first and second smoothing capacitors is connected to one supply line of the AC power supply means, and the supply line is connected to the frame ground (FG). The connection portion of the second smoothing capacitor has an FG potential (for example, constant at 0 V). Therefore, on the basis of the potential of 0 V, the positive DC voltage VD1 due to the charge charged in the first smoothing capacitor and the negative DC voltage −VD2 (| v1D | == the negative DC voltage due to the charge charged in the second smoothing capacitor. | −v2D | = VD). Since the first and second smoothing capacitors are connected in series, a voltage (2 × VD) having a potential about twice the potential of each capacitor is generated between them. That is, the AC power supply means, the rectifier circuit, and the smoothing circuit constitute a voltage doubler circuit that boosts the power supply voltage about twice.

Then, a positive direct current output (first direct current output) from one terminal of the first smoothing capacitor serving as the DC link and a negative direct current output from one terminal of the second smoothing capacitor serving as the DC link ( Second DC output) is supplied to the inverter circuit.
The inverter circuit appropriately switches each switching element based on a control signal from the control means, and alternately switches the first DC output and the second DC output to supply the brushless motor. Accordingly, the brushless motor is supplied with an alternating current output of a positive direct current output (VD) and a negative direct current output (−VD) that are alternately switched.

As described above, since the connection portion (middle point) of the first and second smoothing capacitors is constant at the FG potential, even if currents flowing through the floating capacitances Cs and FG due to switching of the switching element flow to each circuit. The DC output of the smoothing circuit (DC link output) is not affected by fluctuations in the AC power supply.
As a result, the inverter circuits can be stably supplied with the DC voltages VD and -VD that are not affected by the fluctuation of the power supply. Therefore, compared with the conventional DC link configuration, the brushless motor due to the fluctuation of the AC power supply. It is possible to suppress the occurrence of minute vibrations of the position deviation.

  [Invention 2] Further, the motor control device of Invention 2 is the motor control device of Invention 1, wherein the brushless motor is a three-phase brushless motor having first to third windings, and the switching element is the first. 1 to 6 transistors, and the inverter circuit includes a first half-bridge circuit having a configuration in which the first and second transistors are connected in series, and a configuration in which the third and fourth transistors are connected in series. A second half bridge circuit and a third half bridge circuit having a configuration in which the fifth and sixth transistors are connected in series, and the first to third half bridge circuits are connected in parallel. The series connection of the first and second transistors is electrically connected to one end of the first winding, and the series connection of the third and fourth transistors is connected to the second winding. Electrically connected to one end, electrically connecting a series connection of the fifth and sixth transistors to one end of the third winding, and a high potential of the first to third half-bridge circuits The parallel connection portion on the side is electrically connected to the one terminal of the first smoothing capacitor, and the parallel connection portion on the low potential side of the first to third half bridge circuits is connected to the second terminal. A high potential of the first to third half bridge circuits electrically connected to the one terminal of the smoothing capacitor and based on the control signal supplied to the drive terminals of the first to sixth transistors. The first DC output is supplied to the first to third windings by turning on the transistor on the side, and the first to third windings of the first DC output by turning off the transistor on the side. The supply to the line is stopped, and the first to third parts are based on the control signal. The second DC output is supplied to the first to third windings by turning on the low-potential-side transistor of the roof bridge circuit, and the second DC output is turned off. The supply to the first to third windings is stopped.

  With such a configuration, the driving power of the voltage VD is supplied to the brushless motor by controlling on / off of the transistors on the high potential side (high side) of the first to third half bridge circuits. It is possible to control whether or not, and by controlling on / off of the low potential side (low side) transistors of the first to third half bridge circuits, the driving power of the voltage −VD is applied to the brushless motor. Whether to supply or not can be controlled.

  In other words, switching control that turns off the low-side transistor when the high-side transistor in each half-bridge circuit is turned on and turns on the low-side transistor when the high-side transistor is turned off. By performing, it is possible to easily generate the three-phase AC power supplied to the three-phase brushless motor.

  [Invention 3] Further, the motor control device of Invention 3 is the motor control device of Invention 1 or 2, wherein the control means generates a PWM (pulse width modulation) signal as the control signal, and the PWM signal is converted into the inverter. By supplying to the circuit, the duty ratio of the AC output composed of the first DC output and the second DC output alternately output to the brushless motor is controlled.

With such a configuration, the control means generates the PWM signal as a control signal for controlling the switching operation of the switching element of the inverter circuit, so this PWM signal is used as the first to sixth transistors of the inverter circuit. By supplying to the driving terminal, the on time and off time of each transistor can be easily controlled.
Thereby, the variable speed drive control of the brushless motor can be easily performed.

[Invention 4] Furthermore, the motor control device of Invention 4 is the motor control device of any one of Inventions 1 to 3, wherein the motor control device is connected between the one terminal of the second smoothing capacitor and the frame ground. A capacitor for noise suppression is provided.
With such a configuration, noise from the power supply line can be suppressed by the noise suppressing capacitor, so that occurrence of minute vibrations of position deviation due to the noise can be suppressed.

[Invention 5] In order to achieve the above object, the motor control device of Invention 5 is a motor control device for controlling the operation of a brushless motor,
AC power supply means having a configuration in which two supply lines for supplying AC power are provided, and one of the two supply lines is electrically connected to the frame ground;
A full-wave rectifier circuit configured to full-wave rectify the AC input from the AC power supply means;
Including a first smoothing capacitor and a second smoothing capacitor, connecting the first smoothing capacitor and the second smoothing capacitor in series, and electrically connecting the series connection portion to the one supply line; A smoothing circuit configured to smooth the rectified input from the full-wave rectifier circuit and boost the voltage to a double voltage by the first and second smoothing capacitors;
Including a plurality of switching elements, and supplying a first DC output from the first smoothing capacitor and a second DC output from the second smoothing capacitor to the brushless motor via the switching element. An inverter circuit configured to perform switching operation of the plurality of switching elements to alternately switch the first DC output and the second DC output to the brushless motor;
Control means for generating a control signal for controlling the switching operation of the inverter circuit based on the rotational position detected by the position detecting means for detecting the rotational position of the brushless motor, and supplying the control signal to the switching element; Is provided.
With such a configuration, it is possible to obtain operations and effects equivalent to those of the first aspect.

  As described above, according to the motor control devices of the inventions 1 to 3 and 5, the rectified input from the full-wave rectifier circuit is smoothed and doubled to construct a voltage doubler circuit that generates a direct current output. The series connection of the first smoothing capacitor and the second smoothing capacitor is connected to the AC power supply line connected to the ground, and the potential of the series connection of the first and second smoothing capacitors is set to a constant potential ( FG potential), when the switching element of the inverter circuit is switched, even if a current flows through the floating capacitance Cs, the DC output supplied to the inverter circuit is not affected by the fluctuation of the AC power supply. Thus, the effect of suppressing the occurrence of minute vibrations in the positional deviation of the brushless motor due to power fluctuations can be obtained.

  Furthermore, according to the motor control device of the invention 4, in addition to the effect of any one of the inventions 1 to 3, a noise suppressing capacitor is connected between one terminal of the second smoothing capacitor and the ground. As a result, it is possible to suppress noise from the power supply line, and to suppress the occurrence of minute vibrations of position deviation due to the noise.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 are diagrams showing an embodiment of a motor control device according to the present invention.
First, the configuration of the motor control device according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a motor control device 100 according to the present embodiment.
As shown in FIG. 1, the motor control device 100 is a device that controls the operation of the brushless motor 200, and is an AC power supply unit that supplies AC power from a commercial AC power supply (AC100 [V]) to a subsequent circuit. 10, a full-wave rectifier circuit 11 that full-wave rectifies the AC input from the AC power supply unit 10, a smoothing circuit 12 that smoothes the rectified input from the full-wave rectifier circuit 11 and generates a DC output, A direct current output generated by the circuit 12 is converted into an alternating current output, and this alternating current output is supplied to the brushless motor 200 via the electric cable 20 and a command from the microcomputer 16 (hereinafter referred to as the microcomputer 16). A control circuit 15 for generating a control signal for controlling the operation of the inverter circuit 13 based on the signal and supplying the control signal to the inverter circuit 13; And a microcomputer 16 that generates a command signal based on position signals from the Hall elements Hu, Hv, and Hw for detecting the rotor rotational position of the motor 200 and supplies the generated command signal to the control circuit 15. Is done.

  The AC power supply unit 10 includes the two power supply lines of a commercial AC power supply (hereinafter simply referred to as a commercial power supply) having a configuration in which one of the two power supply lines is grounded to a frame ground (FG). Are provided with a first supply line and a second supply line, respectively. Of the first and second supply lines, the first supply line is electrically connected to the power supply line supplying the commercial power, and the second supply line is grounded to the commercial power supply FG. Is electrically connected to the other power supply line.

The full-wave rectifier circuit 11 includes four rectifier diodes, and each two diodes of the four diodes are connected in series in the forward direction, and one set of anodes connected in series and the other set of anodes are connected to each other. Electrically connected, one set of cathodes and the other set of cathodes are electrically connected to form a diode bridge circuit.
Further, one set of series connection portions constituting the diode bridge circuit is electrically connected to the first supply line of the AC power supply unit 10, and the other series connection portion is connected to the AC power supply unit 10. The second supply line is electrically connected.

  The smoothing circuit 12 includes a first smoothing capacitor C1 and a second smoothing capacitor C2, and these C1 and C2 are electrically connected in series, and the series connection is a second supply line of the AC power supply unit 10. And is electrically connected. Further, the terminal of C1 which is not connected in series is electrically connected to the connection part on the cathode side of the diode bridge circuit. Hereinafter, this connection portion is referred to as a DC link point P. Further, the terminal of C2 that is not connected in series is electrically connected to the anode side connecting portion of the diode bridge circuit. Hereinafter, this connection portion is referred to as a DC link point N. The DC link point N is connected to the FG via a noise suppressing capacitor Ca for suppressing noise from the power supply line.

The first and second smoothing capacitors C1 and C2 are capacitors having a capacity and a withstand voltage necessary for stable operation of the brushless motor 200, and both have the same performance (capacity and withstand voltage are the same). To use.
Moreover, since the commercial power source is AC100V, and the direct connection portion between the first smoothing capacitor C1 and the second smoothing capacitor C2 is connected to the second supply line, the connection portion between C1 and C2 (hereinafter, the middle The point M) is constant at the potential of FG (0 [V]). Therefore, the potential at the DC link point P (the potential between P- (C1) -FG) becomes +141 [V] due to the charge charged at C1, and the potential at the DC link point N (N) due to the charge charged at C2. − (C2) −FG potential) is −141 [V]. Accordingly, the voltage between P and N is 282 [V], and the full-wave rectified output (141 [V] peak) of the full-wave rectifier circuit is boosted to twice that voltage. That is, the AC voltage supply unit 10, the full-wave rectifier circuit 11, and the smoothing circuit 12 constitute a voltage doubler circuit 14.

The inverter circuit 13 includes insulated gate bipolar transistors (IGBT) Tr1 to Tr6. Tr1 and Tr2 are connected in series to form a first half bridge circuit, Tr3 and Tr4 are connected in series to form a second half bridge circuit, and Tr5 and Tr6 are connected in series to form a first half bridge circuit. 3 half-bridge circuits.
Further, these first to third half bridge circuits are connected in parallel, the parallel connection on the Tr1, Tr3 and Tr5 side is connected to the DC link point P, and the parallel connection on the Tr2, Tr4 and Tr6 side is Are connected to the DC link point N.

  Furthermore, the series connection portion of Tr1 and Tr2 is electrically connected to the U-phase electric element winding of the brushless motor 200 via the electric cable 20, and the series connection portion of Tr3 and Tr4 is connected via the electric cable 20. The series connection portion of Tr5 and Tr6 is electrically connected to the W-phase electrical winding of the brushless motor 200 via the electrical cable 20. ing. Hereinafter, these series connection parts are referred to as power output part O, and the voltage between O-FG is referred to as v_OFG.

The control circuit 15 generates a control signal for on / off control of Tr1 to Tr6 based on a command signal from the microcomputer 16, and supplies the generated control signal to a gate terminal (electrode) that is a drive terminal of Tr1 to Tr6. To do. In the present embodiment, a PWM signal is generated as a control signal.
The microcomputer 16 generates a command signal for causing the brushless motor 200 to perform a rotation operation, a stop operation, and the like based on the position signals from the Hall elements Hu, Hv, and Hw, and supplies the generated command signal to the control circuit 15. To do. That is, feedback control of the brushless motor 200 is performed by the control circuit 15 and the microcomputer 16.

  On the other hand, the brushless motor 200 is a three-phase brushless motor having armature windings corresponding to the U-phase, V-phase, and W-phase, and a Hall element Hu that outputs a position signal of the motor rotor corresponding to each phase. , Hv and Hw. Further, the brushless motor 200 is electrically connected to the inverter circuit 13 of the motor control device 100 via the electric cable 20.

Next, the actual operation of the motor control device 100 having the above configuration will be described with reference to FIGS.
Here, FIG. 2 is a diagram illustrating a path of a current that flows during the switching operation of the inverter circuit 13. FIG. 3 is a diagram illustrating the relationship between the waveform of the voltage v1 of the AC power supply (AC100 [V]) and v_OFG when the three phases are simultaneously switched at a duty ratio of 50 [%].

  When a power switch (not shown) of the motor control device 100 is pressed and AC power from a commercial power supply (AC 100 V) is supplied to the full-wave rectifier circuit 11 via the first supply line of the AC power supply unit 10. In the diode bridge circuit of the full wave rectifier circuit 11, the AC input is full wave rectified. The rectified power subjected to full-wave rectification is input to the smoothing circuit 12 to charge C1 and C2, thereby being smoothed. Specifically, with the middle point M as a reference, the potential of the DC link point P is set to a constant potential of +141 [V], and the potential of the DC link point N is set to a constant potential of −141 [V]. Hereinafter, the DC output at the DC link point P (+141 [V]) is referred to as a first DC output, and the DC output at the DC link point N (−141 [V]) is referred to as a second DC output.

  The DC link point P is connected to the collectors of the transistors Tr1, Tr3, Tr5 on the high potential side of the first to third half bridge circuits, and the DC link point N is connected to the first to third half bridge circuits. Since the transistors Tr2, Tr4, and Tr6 on the low potential side of the circuit are connected to the emitters of the circuit, when Tr1, Tr3, and Tr5 are turned on, the v_OFG of the first to third half bridge circuits is “+141 [V]”. When Tr2, Tr4, and Tr6 are turned on, v_OFG of the first to third half-bridge circuits becomes “−141 [V]”.

On the other hand, when the microcomputer 16 receives position signals from the Hall elements Hu, Hv, and Hw of the brushless motor 200, the microcomputer 16 rotates the rotor of the brushless motor 200 and stops it at a desired rotation position based on the received position signals. The command signal is generated, and the generated command signal is supplied to the control circuit 15.
When the command signal from the microcomputer 16 is supplied, the control circuit 15 generates a PWM signal based on the command signal, and supplies the generated PWM signal to the gate terminals of Tr1 to Tr6 of the inverter circuit 13. This PWM signal is always generated so that when one of Tr1, Tr3, and Tr5 is on, the one that is turned on among Tr2, Tr4, and Tr6 is turned off.

  When a PWM signal is supplied to the gate terminals of Tr1 to Tr6, Tr1 to Tr6 are turned on / off to perform a switching operation. As a result, the first DC output and the second DC output are alternately switched and supplied to the electric coil of each phase of the brushless motor 200. That is, a three-phase AC signal is supplied to each armature winding of the brushless motor 200. The three-phase alternating current signal functions as a speed command signal, and the rotation speed of the motor can be decreased as the pulse width of the PWM signal is increased, and the rotation speed of the motor can be increased as the width is decreased. .

  When the three-phase AC signal from the inverter circuit 13 is supplied to the electric windings of each phase of the brushless motor 200, the rotor rotates at a speed corresponding to the pulse width of the supply signal and stops supplying the three-phase AC signal. As a result, the rotation of the rotor stops. That is, a three-phase AC signal is generated by the PWM signal, the brushless motor 200 is driven at a variable speed by the three-phase AC signal, rotated to a desired rotation position, and the supply of the three-phase AC signal is stopped and stopped at the desired position. This completes positioning.

When this positioning is completed, if any of Tr1 to Tr6 performs a switching operation, each circuit of the motor control device 100 is supplied with current through the floating capacitances Cs and FG generated between the electric cable 20 and FG. Flows.
As shown in FIG. 2, this current path is “P → O → Cs → FG → M → C1 → P (solid line in FIG. 2)” when Tr1 on the high potential side is switched. The same applies to Tr3 and Tr5.

On the other hand, Tr2 on the low potential side is “N → C2 → FG → Cs → O → N (dotted line in FIG. 2)” during switching. The same applies to Tr4 and Tr6.
In the present embodiment, since the potential at the midpoint M, which is a connection portion between C1 and C2, is constant at “0 [V]”, even if Tr1 is switched, a current flows through the solid line. Therefore, v_OFG is constant at “+141 [V]”. Further, even if Tr2 is switched, a current flows through the path of the one-dot chain line, so v_OFG is constant at “−141 [V]”. That is, even if a current flows through Cs by switching Tr1 and Tr2, fluctuations in the AC power supply do not affect the potentials of the DC link points P and N.

Therefore, as shown in FIG. 3, the relationship between the voltage waveform of the commercial power supply and v_OFG is that v_OFG is always a constant voltage (+141 [V] and −141 [V]) even if the voltage of the commercial power supply changes. Thus, a mountain-like shape with a ½ cycle as seen in the prior art does not occur.
That is, since the fluctuation of v_OFG due to the switching operation at the time of completion of positioning does not occur, the minute vibration of the positional deviation of the brushless motor 200 due to this does not occur, so that highly accurate positioning can be performed. In FIG. 3, the horizontal axis represents time [ms] and the vertical axis represents voltage [V].

Furthermore, since the power supply line noise can be suppressed by the noise suppression capacitor Ca connected between the DC link N point and the FG, it is possible to suppress the occurrence of minute vibration of the position deviation due to the power supply line noise, More accurate positioning can be performed.
As described above, the motor control device 100 according to the present embodiment electrically connects the supply line on the AC power supply side of the commercial power supply and the first supply line of the AC power supply unit 10, and The supply line connected to the FG is electrically connected to the second supply line of the AC power supply unit 10, and the smoothing circuit 12 is connected in series with the first smoothing capacitor C1 and the second smoothing capacitor C2. In addition, the serial connection portion and the second supply line are electrically connected. Furthermore, one set of series connection portions of the diode bridge circuit is electrically connected to the first supply line, and the other series connection portion is electrically connected to the second supply line. The connection portion is electrically connected to a terminal on the opposite side to the series connection side of C1, and the connection portion on the anode side is electrically connected to a terminal on the opposite side to the series connection side of C2. That is, the AC power supply unit 10, the full-wave rectifier circuit 11, and the smoothing circuit 12 constitute a voltage doubler circuit.

As a result, the potential of the connection portion between C1 and C2 becomes constant at the potential of FG. For example, the transistor of the inverter circuit 13 performs a switching operation when positioning is completed, and a current flows through each circuit through the floating capacitance Cs. However, since a current path passing through the commercial power source is not formed, the potentials of the DC link points P and N can be made constant.
Furthermore, since Ca is connected between the DC link point N and FG, it is possible to suppress power line noise.

  In the said embodiment, Hall element Hu, Hv, and Hw respond | corresponds to the position detection means of the invention 1 or 5, and the alternating current power supply part 10 respond | corresponds to the alternating current power supply means of the invention 1 or 5. The full-wave rectifier circuit 11 corresponds to the full-wave rectifier circuit described in the invention 1 or 5, the smoothing circuit 12 corresponds to the smoothing circuit described in the invention 1 or 5, and the inverter circuit 13 corresponds to the inventions 1 and 2. 3 to 5 corresponds to the inverter circuit described in any one of 5 and 5, Tr1 to Tr6 correspond to the switching element described in any one of inventions 1, 2, and 5, and the noise suppression capacitor Ca corresponds to the invention 4 The electronic coil corresponds to the winding described in Invention 2, the control circuit 15 and the microcomputer 16 correspond to any one of Inventions 1, 3, and 5. Corresponding to the control means

In the embodiment described above, a commercial power supply of 100 V has been described as an example of the AC power supply. However, the present invention is not limited to this, and AC power from an AC power supply corresponding to another voltage may be supplied.
In the above embodiment, a three-phase brushless motor has been described as an example of a brushless motor. However, the present invention is not limited to this, and may be applied to a brushless motor having another configuration such as a two-phase brushless motor.

In the above embodiment, the full-wave rectifier circuit 11 has a configuration in which four diodes are bridge-connected. However, the present invention is not limited to this. A circuit configuration using five or more may be used.
Moreover, in the said embodiment, although the switching element which comprises the inverter circuit 13 was IGBT, not only this but the performance required in order to drive brushless motors, such as a pressure | voltage resistant characteristic and current supply capability, is satisfy | filled. If present, other transistors such as a bipolar transistor, a field effect transistor (FET), and a MOSFET may be used.

2 is a block diagram showing a configuration of a motor control device 100. FIG. 3 is a diagram illustrating a path of a current that flows during a switching operation of the inverter circuit 13. FIG. It is a figure which shows the voltage waveform of alternating current power supply (AC100 [V]) when switching 3 phases simultaneously by duty ratio 50 [%], and v_OFG. It is a circuit diagram which shows the structure of the conventional motor control apparatus. It is a figure which shows the mode of the voltage division of DC link voltage. It is a figure which shows a current pathway when a power supply voltage becomes below the output voltage of an inverter. It is a figure which shows a current pathway when a power supply voltage becomes larger than the output voltage of an inverter. The figure which shows the relationship between the waveform of AC power supply (v1, v2), v_OFG, and v_NFG when the switching element of the inverter circuit in the motor control device of the conventional configuration is simultaneously switched at three phases with a duty ratio of 50 [%]. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Motor control apparatus 200 Brushless motor 10 AC power supply part 11 Full wave rectifier circuit 12 Smoothing circuit 13 Inverter circuit 14 Voltage doubler circuit 15 Control circuit 16 Microcomputer 20 Electric cable C1 1st smoothing capacitor C2 2nd smoothing capacitor Tr1 Tr6 IGBT
Ca noise suppression capacitor Hu, Hv, Hw Hall element Cs Floating capacitance

Claims (5)

A motor control device for controlling the operation of a brushless motor,
AC power supply means configured to have two supply lines for supplying AC power, and one of the two supply lines is electrically connected to the frame ground;
Two sets of two diodes connected in series in the forward direction are included, and the two sets of anode-side terminals and cathode-side terminals are electrically connected to form a diode bridge circuit. One series connection part of the set is electrically connected to the one supply line, the other series connection part is electrically connected to the other of the supply lines, and the AC power is supplied by the diode bridge circuit. A full-wave rectifier circuit configured to full-wave rectify the AC input from the supply means;
A first smoothing capacitor and a second smoothing capacitor, wherein one terminal of the first smoothing capacitor is electrically connected to a connection portion on a cathode side of the diode bridge circuit; One terminal is electrically connected to the connecting portion on the anode side, the other terminals of the first and second smoothing capacitors are electrically connected, and the connecting portion is electrically connected to the one supply line. A smoothing circuit configured to smooth the rectified input from the full-wave rectifier circuit and boost the voltage to a double voltage by the first and second smoothing capacitors;
A first DC output from the one terminal of the first smoothing capacitor; and a second DC output from the one terminal of the second smoothing capacitor. And an inverter circuit configured to supply the brushless motor by alternately switching the first DC output and the second DC output by switching the plurality of switching elements through the switching element. When,
Control means for generating a control signal for controlling the switching operation of the inverter circuit based on the rotational position detected by the position detecting means for detecting the rotational position of the brushless motor, and supplying the control signal to the switching element; A motor control device comprising: The brushless motor is a three-phase brushless motor having first to third windings,
The switching element includes first to sixth transistors,
The inverter circuit includes a first half bridge circuit having a configuration in which the first and second transistors are connected in series, and a second half bridge circuit having a configuration in which the third and fourth transistors are connected in series. A third half-bridge circuit having a configuration in which the fifth and sixth transistors are connected in series, the first to third half-bridge circuits being connected in parallel, and the first and second transistors And a series connection of the third and fourth transistors is electrically connected to one end of the second winding, and the first connection is electrically connected to one end of the first winding. 5 and the sixth transistor are connected in series to one end of the third winding, and the parallel connection on the high potential side of the first to third half bridge circuits is connected to the first winding. One end of the smoothing capacitor And electrically connecting the parallel connection portion on the low potential side of the first to third half-bridge circuits with the one terminal of the second smoothing capacitor, Based on the control signal supplied to each drive terminal of the sixth transistor, the high potential side transistors of the first to third half-bridge circuits are turned on, whereby the first DC output is The first to third windings are supplied and turned off to stop the supply of the first DC output to the first to third windings. Based on the control signal, the first to third windings are stopped. The second DC output is supplied to the first to third windings by turning on the low-potential side transistor of the third half bridge circuit, and the second DC output is turned off. It is configured to stop the supply of DC output to the first to third windings. The motor control device according to claim 1, wherein the door.   The control means generates a PWM (Pulse Width Modulation) signal as the control signal, and supplies the PWM signal to the inverter circuit, whereby the first DC output alternately output to the brushless motor and the The motor control device according to claim 1 or 2, wherein a duty ratio of an AC output composed of the second DC output is controlled.   The motor according to any one of claims 1 to 3, further comprising a noise suppression capacitor connected between the one terminal of the second smoothing capacitor and the frame ground. Control device. A motor control device for controlling the operation of a brushless motor,
AC power supply means having a configuration in which two supply lines for supplying AC power are provided, and one of the two supply lines is electrically connected to the frame ground;
A full-wave rectifier circuit configured to full-wave rectify the AC input from the AC power supply means;
Including a first smoothing capacitor and a second smoothing capacitor, connecting the first smoothing capacitor and the second smoothing capacitor in series, and electrically connecting the series connection portion to the one supply line; A smoothing circuit configured to smooth the rectified input from the full-wave rectifier circuit and boost the voltage to a double voltage by the first and second smoothing capacitors;
Including a plurality of switching elements, and supplying a first DC output from the first smoothing capacitor and a second DC output from the second smoothing capacitor to the brushless motor via the switching element. An inverter circuit configured to perform switching operation of the plurality of switching elements to alternately switch the first DC output and the second DC output to the brushless motor;
Control means for generating a control signal for controlling the switching operation of the inverter circuit based on the rotational position detected by the position detecting means for detecting the rotational position of the brushless motor, and supplying the control signal to the switching element; A motor control device comprising:

Images