JP2014003840A - Motor control device and air conditioner - Google Patents

Abstract

To provide a motor control device capable of suppressing a decrease in reliability due to submersion and condensation of a motor without increasing costs.
An inverter 12 that drives a brushless DC motor 6 having a position detection circuit 63 that detects position information of a rotor 62, and a control unit 11 that generates a signal for driving the inverter 12 using the position information are provided. The motor control device 1 supplies DC power to the position detection circuit 63, and is inserted in series with respect to a power supply line supplying DC power to the position detection circuit 63, and controls supply of power to the position detection circuit 63. When the position information is not required, the control unit 11 opens the contact of the opening / closing unit 100.
[Selection] Figure 1

Description

  The present invention relates to a brushless DC (Direct Current) motor control device and an air conditioner.

  A brushless DC motor needs to apply an AC voltage that is synchronized with the position of the magnetic pole of the rotor. Therefore, a position detection circuit that detects the magnetic pole position of the Hall element, etc. is installed in the motor, and an electric signal corresponding to the magnetic pole position is generated. Many methods are used. On the other hand, in an environment where the circuit may be submerged or condensed, it is necessary to perform waterproofing such as potting in order to prevent circuit corrosion due to leakage current.

  The position detection circuit of the brushless DC motor is installed only in the vicinity of the rotor, but it may be difficult to add a waterproof structure in an environment where the dimensional restrictions in the vicinity of the motor are severe. In such applications, there is a need for a technique that can take corrosion countermeasures for the position detection circuit at a location away from the brushless DC motor.

  For example, Patent Document 1 below discloses a technique for preventing a malfunction of a motor due to circuit corrosion by applying positive and negative voltages when submerged.

JP 2001-341931 A

  However, the conventional technique represented by Patent Document 1 is a technique for the main winding of the motor, and is not applicable to a single power supply circuit such as a position detection circuit of a brushless DC motor.

  In addition, since the position detection circuit of the brushless DC motor is generally driven by a low-voltage power supply, the inter-pattern distance between the signals in the circuit is designed to be narrow, and corrosion due to leakage current is likely to occur.

  Further, as an environmental condition in which corrosion due to leakage current in the position detection circuit is likely to proceed, there is a condition that the rotor of the brushless DC motor is stopped and the control power supply is energized. When this condition is satisfied, the progress of corrosion is accelerated because a DC electric field is applied around the position detection circuit. The defrosting operation of the outdoor unit for an air conditioner matched the above environmental conditions, and there was a possibility of equipment failure due to corrosion.

  As a method of preventing moisture from entering the fan motor due to condensation due to the above factors, it is conceivable to change to a waterproof structure. However, if the waterproof structure is changed, the motor becomes larger and the cost increases. there were.

  The present invention has been made in view of the above, and an object of the present invention is to provide a motor control device that can suppress a decrease in reliability due to submersion / condensation of the motor without increasing the cost.

  In order to solve the above-described problems and achieve the object, the present invention provides an inverter that drives a brushless motor having a position detection circuit that detects position information of a rotor, and a signal that drives the inverter using the position information. And a controller for generating a DC power supply to the position detection circuit, wherein the position detection circuit is inserted in series with respect to a power supply line supplying the DC power supply to the position detection circuit. An opening / closing unit that controls supply of power to the circuit, and the control unit instructs the opening / closing unit to open a contact of the opening / closing unit when the position information is not required.

  According to the present invention, since the time during which a DC electric field is applied to the position detection circuit is shortened, it is possible to suppress a decrease in reliability due to submersion / condensation of the motor without increasing the cost.

FIG. 1 is a diagram illustrating a configuration example of a motor control device according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration example of the Hall IC. FIG. 3 is a diagram illustrating a configuration example of the position detection circuit. FIG. 4 is a diagram illustrating an example of the positional relationship between the Hall ICs. FIG. 5 is a time chart illustrating an example of the control signal OC and the position signal input to the opening / closing unit. FIG. 6 is a schematic diagram of electrolysis. FIG. 7 is a diagram illustrating a configuration example of a motor control device that outputs a control signal OC according to an operation command from the outside. FIG. 8 is a diagram illustrating a relationship between a DC power source and a load of the outdoor unit of the air conditioner. FIG. 9 is a diagram illustrating a main circuit configuration example of the air conditioner.

  Embodiments of a motor control device and an air conditioner according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a motor control device 1 according to the present invention. As shown in FIG. 1, the motor control apparatus 1 of this Embodiment is connected with the brushless DC motor 6, and controls the brushless DC motor 6 (brushless motor). The motor control device 1 includes a control unit 11, an inverter 12, a control power supply 13, and an opening / closing unit 100 as main components.

  The brushless DC motor 6 includes a stator 61 that converts AC power from the inverter 12 into a rotating magnetic field, a rotor 62 that has a permanent magnet, generates rotational torque in synchronization with the rotating magnetic field generated by the stator 61, and the stator 61. And a position detection circuit 63 that detects the magnetic flux of the permanent magnet of the rotor 62 and outputs a signal.

  The brushless DC motor 6 does not have a power supply circuit for the position detection circuit 63 therein, and is supplied with a power supply voltage generated by receiving a voltage supply from an external power supply, for example, from the control power supply 13 or the like in the motor control device 1. The position detection circuit 63 receives Vcc and GND_2 (ground) as control DC power generated by the motor control device 1 via the power supply lines 64-1 and 64-2, and detects and detects the magnetic pole position of the rotor. As a result, position signals (position information) HU, HV, and HW are output. Based on the position signals HU, HV, HW and an operation command given from the outside, the control unit 11 generates a PWM signal of an applied voltage for rotating the brushless DC motor 6 and inputs the PWM signal to the inverter 12. The inverter 12 outputs U-phase, V-phase, and W-phase AC voltages U, V, and W to the brushless DC motor 6 in accordance with the PWM signal.

  The open / close unit 100 includes an open / close terminal and a control terminal. The open / close terminal is connected in series to at least one of power supply lines 64-1 and 64-2 for driving the position detection circuit 63, and the control terminal is It is connected to the control unit 11 through a control signal line.

  Next, the internal configuration of the position detection circuit 63 will be described with reference to FIGS. 2 is a diagram illustrating a configuration example of a Hall IC (Integrated Circuit), FIG. 3 is a diagram illustrating a configuration example of the position detection circuit 63, and FIG. 4 is a diagram illustrating an example of a positional relationship of the Hall IC. .

  The Hall IC 101 is an IC for detecting a change in a magnetic field, and includes a Hall element 110, an amplifier 111, a hysteresis comparator 112, a transistor 113, and a pull-up resistor 114. The Hall element 110 is an element that outputs a voltage corresponding to the magnitude and polarity of the magnetic flux. In the Hall IC 101, the Hall element 110 outputs a voltage corresponding to the alternating magnetic field of the rotor 62, the amplifier 111 amplifies this voltage, and the hysteresis comparator 112 binarizes it. The binarized signal is output via the transistor 113 and the pull-up resistor 114. Hall IC 101 has power supply terminals 115-1 and 115-2 because Hall element 110 is driven by voltage.

  As shown in FIGS. 3 and 4, the position detection circuit 63 includes three Hall ICs 101 shown in FIG. 3 and 4, these are shown as H (Hall IC) 101a, 101b, and 101c, respectively. As shown in FIG. 4, the Hall ICs 101a, 101b, and 101c are arranged coaxially with the rotor 62 and in a positional relationship in which the magnetic phases are equidistant (θ = 2π / 3). The Hall ICs 101a, 101b, and 101c correspond to the U phase, the V phase, and the W phase, respectively. In addition, common power supply voltages Vcc and GND are supplied to the three Hall ICs 101a, 101b, and 101c from the power supply terminals 102-1 and 102-2 of the position detection circuit 63.

  Next, the operation of the present embodiment will be described with reference to FIGS. FIG. 5 is a time chart showing an example of the control signal OC and the position signal input to the opening / closing unit 100, and FIG. 6 is a schematic diagram of electrolysis.

  As described above, the control unit 11 generates a PWM signal for rotationally driving the brushless DC motor 6, and also generates a control signal OC for controlling the opening / closing unit 100 and inputs the control signal OC to the opening / closing unit 100. When High is input as the control signal OC, the opening / closing unit 100 closes the opening / closing terminal, whereby the power supply voltage GND_2 is supplied to the position detection circuit 63. When Low is input as the control signal OC, the open / close unit 100 opens the open / close terminal, whereby the power supply voltage GND_2 is not supplied to the position detection circuit 63.

  First, operations of the control signal OC and the position signal for controlling the opening / closing unit 100 will be described with reference to FIG. FIG. 5A is a time chart during rotation of the rotor. When the control signal OC is High, the power supply voltage GND_2 is applied to the position detection circuit 63, and output signals of the three-phase Hall ICs 101a, 101b, 101c corresponding to the magnetic pole positions of the rotor are obtained as the position signals HU, HV, HW. . The operation in the state where the control signal OC is High is the same as that of a conventional general position detection circuit that does not include the opening / closing unit 100.

  On the other hand, when the control signal OC is Low, the power supply voltage GND_2 is not applied to the position detection circuit 63, and the output signals of the Hall ICs 101a, 101b, 101c (that is, the position signals HU, HV, HW) are not generated. In this case, the position signals HU, HV, and HW remain at the high level because the position signals HU, HV, and HW are the power supply terminals to which the pull-up resistor 114 in the Hall IC 101 is applied with the power supply voltage Vcc. This is due to the connection with 115-1.

  Next, the operation while the rotor is stopped will be described with reference to FIG. When the control signal OC becomes High, the magnetic field applied to the Hall ICs 101a, 101b, and 101c does not change while the rotor is stopped (section # 1 in FIG. 5 (b)), so the output is fixed. At this time, the potentials of some of the position signals HU, HV, HW and the power supply voltage GND_2, which are internal potentials, are fixed at the low level (indicated by black circles in FIG. 5B). This is because, according to the wiring pattern in the substrate, a DC voltage is generated between the wiring pattern of a signal (indicated by a white circle in FIG. 5B) that generates a high potential including Vcc.

  Next, the relationship between the state in which moisture containing an electrolyte is attached between two wiring patterns and the voltage will be described with reference to FIG. FIG. 6A shows a case where there is no potential difference between the wiring patterns, and FIG. 6B shows a case where there is a potential difference between the wiring patterns. When there is no potential difference between the wiring patterns, there is no movement of ions in the electrolytic solution, and no chemical reaction due to oxidation / reduction of ions on the copper foil contact surface occurs. On the other hand, when a voltage is applied, ions in the electrolytic solution are attracted to the wiring pattern as an electrode, causing electrolysis at the copper foil contact surface, and depositing a copper compound on the low potential side copper foil, that is, causing corrosion. .

  As described above, the voltage in the position detection circuit 63 becomes a factor that accelerates corrosion between the wiring patterns. On the other hand, when the control signal OC is Low (section # 2 in FIG. 5 (b)), the potentials of the respective wirings in the position detection circuit 63 are all fixed to High, so that electrolysis does not occur even when the electrolytic solution adheres. It is not accelerated, and the progress of corrosion is remarkably suppressed as compared with the case where there is a potential difference.

  Accordingly, the control unit 11 sets the position signals HU, HV, and HW in a necessary condition (for example, when the operation command for the brushless DC motor 6 is ON and the brushless DC motor 6 is operated), that is, the control signal OC is set to High. In situations where HU, HV, and HW are not required (when the motor is stopped, for example), the corrosion of the pattern in the position detection circuit 63 can be suppressed by setting the control signal OC to Low. In particular, in an air conditioner outdoor unit or the like, corrosion is likely to occur when the rotor of the brushless DC motor 6 is stopped and the power supply is energized. However, in this embodiment, the control signal OC is set to Low while the rotor is stopped. By doing so, corrosion can be prevented.

  In the present embodiment, the control unit 11 generates the control signal OC in accordance with the operation status of the brushless DC motor 6, but the control signal OC is included in the operation command input from the outside. May be. FIG. 7 is a diagram illustrating a configuration example of a motor control device that outputs a control signal OC according to an operation command from the outside. The configuration example of FIG. 7 is the same as the configuration example of FIG. 1 except that the control unit 11 is replaced with the control unit 11a. 7, components having the same functions as those in FIG. 1 are denoted by the same reference numerals as those in FIG.

  In the example of FIG. 7, the control unit 11a outputs a signal input as an operation command as the control signal OC. Thereby, it becomes possible to control the opening / closing part 100 from the outside. For example, when the operation command is OFF (command indicating that the brushless DC motor 6 is not operated), the control signal OC is set to Low. In the case of this configuration, there is an advantage that a change from the conventional part of the control unit is almost unnecessary, and the addition to the existing apparatus is easy.

  The opening / closing unit 100 may be anything that can open and close a circuit, and a relay, a transistor, or the like is applicable. Although FIG. 1 shows an example in which a transistor is used for the opening / closing part 100, the transistor has an advantage that it can be made smaller and cheaper than a relay or the like as a device.

  Further, the insertion position of the opening / closing unit 100 is not limited to the GND (ground) side (power supply line 64-2), but is functionally problematic even at a position where it is inserted and opened in series with the power supply line 64-1 on the Vcc side. Absent. FIG. 1 shows an example in which the opening / closing unit 100 provided with a transistor and including a transistor is used. However, the NPN type transistor is less expensive, and the opening / closing unit 100 is provided on the GND side as a configuration using the NPN type. Thus, there is an advantage that the base power supply can be configured non-insulated and inexpensive.

Embodiment 2. FIG.
Next, an example in which the motor control device according to the present invention is applied to an air conditioner will be described as a second embodiment. FIG. 8 is a diagram illustrating an example of a relationship between a DC power source and a load of an outdoor unit of an air conditioner, and FIG. 9 is a diagram illustrating a main circuit configuration example of the air conditioner.

  As a method of suppressing corrosion in a situation where position detection is unnecessary, a method of turning off all the power sources of the motor control device 1 is conceivable. The control using the opening / closing unit 100 described in the first embodiment is effective. In the present embodiment, an example of an application in which the control power supply itself cannot be shut off will be described using an air conditioner.

  As shown in FIG. 9, the air conditioner includes a power supply 201, a rectifier circuit 202, a compressor inverter (INV) 203, a compressor motor 204, a fan inverter (INV) 205, a fan motor 206, and a control circuit 207. In general, in an air conditioner, as shown in FIG. 9, a compressor inverter 203 that drives a compressor motor 204 for circulating a refrigerant and a fan inverter 205 that drives a fan motor 206 share a rectifier circuit 202. Configured. Therefore, if the power supply 201 is shut down to prevent corrosion of the fan motor 206, the compressor cannot be operated alone such as a defrosting operation, and the function as an air conditioner is lacking. Further, the main circuit has a large rated current, and the cost of the circuit element that interrupts the main circuit also increases. Therefore, the cost of the method described in the first embodiment is lower than that of shutting off the power supply of the main circuit.

  As shown in FIG. 8, the DC power supply 121 of the outdoor unit of the air conditioner has various DC loads such as a microcomputer 123, a relay 124, and a communication circuit 125 in addition to the position detection circuit 122 of the fan motor 206. Power is supplied from the power supply circuit, and the cost of the circuit element that cuts off all of them is also increased. Therefore, the cost of the method described in the first embodiment is lower than that of shutting off the power supply of the main circuit.

  From the above, in the air conditioner, the fan motor 206 and the fan inverter 205 are the brushless DC motor 6 and the motor control device 1 of the first embodiment, respectively, thereby preventing corrosion of the position detection circuit 63 at low cost. be able to. Note that a part of the motor control device 1 may be included in the control circuit 207.

  As described above, the motor control device and the air conditioner according to the present invention are useful for a device using a brushless DC motor, and are particularly suitable for a device used in an environment where corrosion easily occurs.

DESCRIPTION OF SYMBOLS 1 Motor control apparatus 6 Brushless DC motor 11, 11a Control part 12 Inverter 13 Control power supply 61 Stator 62 Rotor 63 Position detection circuit 64-1, 64-2 Power supply line 100 Opening / closing part 101, 101a, 101b, 101c Hall IC
102-1, 102-2, 115-1, 115-2 Power supply terminal 110 Hall element 111 Amplifier 112 Hysteresis comparator 113 Transistor 114 Pull-up resistor 121 DC power supply 122 Position detection circuit 123 Microcomputer 124 Relay 125 Communication circuit 201 Power supply 202 Rectifier circuit 203 Compressor inverter 204 Compressor motor 205 Fan inverter 206 Fan motor 207 Control circuit

Claims (5)

An inverter that drives a brushless motor having a position detection circuit that detects position information of the rotor, and a control unit that generates a signal for driving the inverter using the position information, and supplies DC power to the position detection circuit A motor control device,
An open / close unit that is inserted in series with respect to a power supply line that supplies the DC power supply to the position detection circuit, and that controls supply of power to the position detection circuit;
When the position information is not required, the control unit controls the contact of the opening / closing unit to be opened.   The motor control according to claim 1, wherein the control unit determines that the position information is not required when an operation command given from the inside or outside is a value indicating that the brushless motor is to be stopped. apparatus.   The motor control device according to claim 2, wherein the opening and closing unit is configured by a transistor.   4. The motor control device according to claim 3, wherein the transistor has an emitter side connected to the ground of the DC power source and a collector side connected to the ground of the position detection circuit.   An air conditioner that drives a fan motor using the motor control device according to any one of claims 1 to 4.

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