JP6211922B2 - Electric compressor - Google Patents

Description

  The present invention relates to an electric compressor, and more particularly to a technique for preventing reverse rotation when a motor is stopped.

  A conventional electric compressor of this type is described in Patent Document 1, for example. The compressor motor control device described in Patent Document 1 is a zero vector energizing means or a positive voltage side for energizing all switching elements on the positive voltage side or the negative voltage side of the motor drive unit 5 device after the operation of the compressor motor is stopped. One of the DC excitation energizing means for energizing one switching element and one switching element on the negative voltage side is actuated by the braking means to prevent reverse rotation of the compressor motor.

JP 2000-287485 A

  However, if the reverse rotation of the compressor motor is completely prevented by the braking means, a differential pressure remains on the discharge side and the suction side in the compressor. For this reason, when restarting, there is a possibility that the motor torque is insufficient and the start-up of the compressor may fail.

  Furthermore, there is an unknown technique that promotes reduction of the differential pressure by intermittently performing reverse rotation prevention control and slowing the reverse rotation speed (Japanese Patent Application No. 2013-220853).

  However, if a start command is input during reverse rotation of the motor, the motor starts to start rotating forward while rotating in reverse. For this reason, the torque required for starting the forward rotation may be unsuccessful because the inertia energy by the reverse rotation of the motor stored in the rotating body such as the motor, the compressor, and the shaft is added.

  The subject of this invention is providing the electric compressor which can eliminate the inertial energy by reverse rotation of a motor and can suppress starting failure.

  A first invention includes a compressor having a rotor and compressing a low-pressure refrigerant into a high-pressure refrigerant by rotation of the rotor, a motor for driving the compressor, and a motor driving unit having a plurality of switching elements connected to the motor And a motor drive control device that drives the motor by controlling on / off of the plurality of switching elements. The motor drive control device performs reverse rotation relaxation control so that the reverse rotation speed becomes less than the reverse rotation speed of the rotor generated by the differential pressure between the high pressure refrigerant and the low pressure refrigerant after stopping the motor. If there is a restart request, all braking control for energizing all high-side or low-side switching elements of the motor drive unit, or energizing one switching element on the high side and one switching element on the low side, or Energize two of the high-side switching elements for the phase and one of the low-side switching elements for the three-phase, or one of the high-side switching elements for the three-phase and the low-side for the three phases After performing full braking control to energize two of the switching elements, the motor is rotated forward.

  In the second aspect of the invention, the motor drive control device, after stopping the motor, causes the reverse rotation speed to be less than the reverse rotation speed of the rotor generated by the differential pressure between the high-pressure refrigerant and the low-pressure refrigerant. When reverse rotation mitigation control is performed and there is a restart request during reverse rotation mitigation control, the reverse rotation mitigation control is stopped or the full opening control for reverse rotation of the motor is performed, and then the motor is rotated forward.

  According to the present invention, when there is a restart request during reverse rotation mitigation control, the control circuit performs all braking control for energizing all switching elements on the high side or low side of the motor drive unit or one switching on the high side. Energize the element and one low-side switching element, or energize two of the three-phase high-side switching elements and one of the three-phase low-side switching elements, or three-phase high After performing full braking control to energize one of the switching elements on the side and two of the switching elements on the low side for three phases, the motor is rotated in the forward direction, so the inertial energy due to the reverse rotation of the motor is eliminated. An electric compressor capable of suppressing start-up failure can be provided.

It is a lineblock diagram showing the electric compressor of a 1st embodiment of the present invention. It is a flowchart which shows operation | movement of the electric compressor of the 1st Embodiment of this invention. Temporal change in the rotational speed of the compressor and the pressure difference between the discharge side and the suction side by the control when there is a restart request after a lapse of a predetermined time from the rotation stop command of the electric compressor of the first embodiment of the present invention FIG. The time difference between the rotational speed of the compressor and the pressure difference between the discharge side and the suction side by the control when there is a restart request before the elapse of a predetermined time from the rotation stop command of the electric compressor according to the first embodiment of the present invention. It is a figure which shows a change. Temporal change in the rotational speed of the compressor and the differential pressure between the discharge side and the suction side by the control when there is a restart request after a lapse of a predetermined time from the rotation stop command of the electric compressor of the second embodiment of the present invention FIG. It is a figure which shows the switching pattern at the time of direct current excitation energization in the reverse rotation relaxation control of the electric compressor of the 1st Embodiment of this invention, and the switching pattern at the time of zero vector energization. It is a figure which shows the switching pattern at the time of direct current excitation energization in the all-braking control of the electric compressor of the 1st Embodiment of this invention, and the switching pattern at the time of zero vector energization.

  Hereinafter, an electric compressor according to an embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration block diagram showing an electric compressor according to a first embodiment of the present invention. The electric compressor shown in FIG. 1 includes an inverter 1, a motor 2, and a compressor 3. The inverter 1 includes a motor drive control device 4 and a motor drive unit 5.

  The motor 2 is a three-phase AC motor, and drives the compressor 3 by being rotated by the AC power of the inverter 1. The inverter 1 converts a direct current from a direct current power source into an alternating current and supplies the alternating current to the motor 2.

  The motor drive unit 5 includes a first series circuit of a high-side switching element Uh and a low-side switching element Ul, a second series circuit of a high-side switching element Vh and a low-side switching element Vl, and a high-side switching The element Wh and the third series circuit of the low-side switching element Wl are connected in parallel.

  Each switching element Uh, Vh, Wh, Ul, Vl, Wl is composed of an IGBT (insulated gate bipolar transistor). A diode is connected in antiparallel between the collector and emitter of each switching element Uh, Vh, Wh, Ul, Vl, Wl.

  One end of the high-side switching element Uh, one end of the high-side switching element Vh, and one end of the high-side switching element Wh are connected to the positive electrode of the DC power supply and one end of the capacitor C1. One end of the low-side switching element Ul, one end of the low-side switching element Vl, and one end of the low-side switching element Wl are connected to the negative electrode of the DC power supply and the other end of the capacitor C1.

  The other end of the high-side switching element Uh and the other end of the low-side switching element Ul are connected to the U phase of the motor 2. The other end of the high-side switching element Vh and the other end of the low-side switching element Vl are connected to the V phase of the motor 2. The other end of the high-side switching element Wh and the other end of the low-side switching element Wl are connected to the W phase of the motor 2.

  The motor drive unit 5 converts the DC current from the DC power source into a three-phase AC current and supplies it to the motor 2 by turning on / off the six switching elements Uh, Ul, Vh, Vl, Wh, Wl. The motor 2 is driven. The motor 2 is composed of a synchronous motor, and is driven to rotate by a three-phase alternating current from the motor drive unit 5 to drive the compressor 3.

  The compressor 3 has a rotor (not shown), and compresses the low-pressure refrigerant into a high-pressure refrigerant by the rotation of the rotor. The motor drive control device 4 is connected to the motor 2 and the motor drive unit 5 to drive the motor 2 and suppress reverse rotation of the motor 2. The motor drive control device 4 is composed of a microcomputer (MCU) and has a memory 12. ing.

  The motor drive control device 4 detects the voltage and current of each phase of the U phase, V phase, and W phase of the motor 2 during normal operation, and detects the position of the rotor in the motor 2 based on the voltage and current of each phase. Then, six control signals G1, G2, G3, G4, G5, and G6 for the six switching elements Uh, Ul, Vh, Vl, Wh, and Wl are generated based on the position of the rotor.

  The motor drive control device 4 applies the generated control signals G1, G2, G3, G4, G5, G6 to the gates of the six switching elements Uh, Ul, Vh, Vl, Wh, Wl, The switching elements Uh, Ul, Vh, Vl, Wh, Wl are turned on / off.

  The motor drive control device 4 detects the position of the rotor in the motor 2 during the reverse rotation relaxation control period (reverse rotation relaxation control time) for relaxing the reverse rotation of the rotor in the compressor 3 after the motor 2 stops. Do not do.

  After the motor 2 is stopped, the motor drive control device 4 performs control for applying a load to the motor 2 in accordance with the control program read from the memory 12 during the reverse rotation relaxation control period. Reverse rotation relaxation control is performed to control the rotor so that it is less than the reverse rotation speed of the rotor generated by the differential pressure with the low-pressure refrigerant. The memory 12 stores a control program.

  As a first method for performing reverse rotation relaxation control, the motor drive control device 4 stops one of the high-side switching elements Uh, Vh, Wh for the three phases of the motor drive unit 5 after stopping the motor 2. One of the three-phase low-side switching elements Ul, Vl, Wl is intermittently turned on, or two of the three-phase high-side switching elements Uh, Vh, Wh and the three-phase switching elements Ul, Vl, Wl One of the low-side switching elements Ul, Vl, Wl is intermittently turned on, or one of the three-phase high-side switching elements Uh, Vh, Wh and the three-phase low-side switching element Ul , Vl and Wl are intermittently turned on. However, the in-phase high-side switching element and the low-side switching element are not turned on at the same time.

  Further, as a second method for performing the reverse rotation relaxation control, the motor drive control device 4 stops all the switching elements Uh, Vh, Wh of the three-phase high-side switching elements after the motor 2 is stopped. All the switching elements Ul, Vl, and Wl on the low side of the phase are turned on simultaneously and intermittently.

  Further, when there is a restart request during the reverse rotation mitigation control, the motor drive control device 4 performs all braking control or high control for energizing all the high-side switching elements or all the low-side switching elements of the motor drive unit 5. One side switching element and one low side switching element are energized, or two of the three-phase high-side switching elements Uh, Vh, Wh and the three-phase low-side switching elements Ul, Vl, Wl Or one of the three-phase high-side switching elements Uh, Vh, Wh and two of the three-phase low-side switching elements Ul, Vl, Wl. After the full braking control is performed, the motor 2 is rotated forward.

  At the time of restart request, the motor drive control device 4 shifts to the full braking control when the differential pressure is less than or equal to a predetermined pressure, and when the differential pressure exceeds the predetermined pressure, the differential pressure becomes less than or equal to the predetermined pressure. Then, the control is shifted to the full braking control.

  The motor drive control device 4 calculates at least one value of the current value supplied immediately before the motor 2 stops or the rotation speed of the motor 2 immediately before the motor 2 stops based on the current information and voltage information from the motor 2. Then, the differential pressure is estimated based on the calculated value.

  Next, the operation of the electric compressor of the first embodiment configured as described above will be described with reference to the flowchart shown in FIG. First, with reference to FIG. 3, a description will be given of control when a restart request is made after a predetermined time has elapsed since the rotation stop command of the electric compressor.

  First, in the normal operation period from time t0 to t1, the motor drive unit 5 is controlled by the control signals G1, G2, G3, G4, G5, and G6 (rotation commands) from the motor drive control device 4, and the AC from the inverter 1 The motor 2 is rotated at a normal rotation speed by the electric power.

  For this reason, the compressor 3 is driven by the rotation of the motor 2, and the low-pressure refrigerant enters the compressor 3. In the compressor 3, the rotor rotates to compress the low-pressure refrigerant and send the high-pressure refrigerant to the discharge side. That is, the electric compressor is operated (step S11).

  Next, when an operation stop command for the electric compressor is sent from the motor drive control device 4 to the motor drive unit 5 at time t <b> 1 (step S <b> 13), each switching element Uh, Vh, Wh, Ul, Vl of the motor drive unit 5. , Wl is stopped. As a result, the electric compressor stops (step S15). Then, the reverse rotation of the rotor of the compressor 3 occurs due to the differential pressure between the high-pressure refrigerant and the low-pressure refrigerant.

  Next, at time t2, the motor drive control device 4 starts reverse rotation relaxation control of the rotor of the compressor 3 (step S17). That is, the motor drive control device 4 performs control to apply a load to the motor 2 after the motor 2 is stopped, so that the reverse rotation speed RV2 is the differential pressure between the high-pressure refrigerant and the low-pressure refrigerant as shown in FIG. The reverse rotation mitigation control is performed to control the rotor to be less than the reverse rotation speed RV1 generated in step 1.

  Specifically, after the motor 2 is stopped, the motor drive control device 4 stops one of the three-phase high-side switching elements Uh, Vh, Wh of the motor drive unit 5 and the three-phase low-side switching element Uh. One of the switching elements Ul, Vl, Wl is intermittently turned on, or two of the high-side switching elements Uh, Vh, Wh for three phases and the low-side switching elements Ul, Vl for three phases , Wl is intermittently turned on, or one of the three-phase high-side switching elements Uh, Vh, Wh and the three-phase low-side switching elements Ul, Vl, Wl Turn on the two intermittently. However, the in-phase high-side switching element and the low-side switching element are not turned on at the same time.

  As another method, after the motor 2 is stopped, the motor drive control device 4 includes all the switching elements Uh, Vh, Wh for the three phases or the switching elements for the low side for the three phases. All the switching elements of Ul, Vl and Wl are turned on simultaneously and intermittently.

  That is, as shown in FIG. 6, by setting the on-duty of the pulse signal to 10 to 20%, for example, a load is intermittently applied to the motor 2, so that the reverse rotation speed RV2 is increased between the high-pressure refrigerant and the low-pressure refrigerant. The rotor is controlled so as to be less than the reverse rotation speed RV1 generated by the differential pressure. That is, reverse rotation mitigation control for mitigating reverse rotation of the rotor is performed.

  Next, the motor drive control device 4 reads the reverse rotation relaxation control time from the memory 12, and determines whether or not the reverse rotation relaxation control time has elapsed since the reverse rotation relaxation control was started (step S19).

  The reverse rotation relaxation control time is determined by the type of compressor, the differential pressure between the discharge side and the suction side of the compressor 3, the capacity of the compressor 3, the moment of inertia of the compressor 3, the friction during operation of the compressor 3, and the like. The

  Next, the motor drive control device 4 stops the reverse rotation relaxation control when the reverse rotation relaxation control time has elapsed from the start of the reverse rotation relaxation control (step S21).

  On the other hand, the motor drive control device 4 determines whether or not an operation command for the electric compressor is input during the reverse rotation relaxation control period (time t2 to t5) (step S23). That is, the motor drive control device 4 determines whether or not there is a restart request.

  When there is a restart request during the reverse rotation relaxation control period (time t2 to t5), the motor drive control device 4 determines whether or not a certain time T has elapsed since the electric compressor stopped (step S24). ).

  In the example shown in FIG. 3, since there is a restart request at time t3 and a certain time T has elapsed since the electric compressor stopped, the motor drive control device 4 stops the reverse rotation mitigation control (step S27). ) All braking control is performed (step S29).

  That is, the motor drive control device 4 performs all braking control by zero-vector energization or all three of the high-side switching elements Uh, Vh, Wh or all low-side switching elements Ul, Vl, Wl of the motor drive unit 5. Energize two of the high-side switching elements Uh, Vh, Wh for the phase and one of the low-side switching elements Ul, Vl, Wl for the three phases, or the high-side switching elements for the three phases One of Uh, Vh, Wh and two of the three-phase low-side switching elements Ul, Vl, Wl are energized, or one high-side switching element and one low-side switching element are energized Full braking control by direct current excitation energization is performed from time t3, and then the motor 2 is rotated forward at time t31.

  This full braking control is performed by direct current excitation energization or zero vector energization shown in FIG. In DC excitation energization or zero vector energization, the on-duty is 80 to 90%, for example, as can be seen from FIG. That is, by increasing the ON time, the rotation of the rotor of the compressor 3 is stopped in a short time.

  Next, with reference to FIG. 4, a description will be given of the control when a restart request is made before a predetermined time has elapsed since the rotation stop command of the electric compressor.

  As shown in FIG. 4, when there is a restart request at time t6 before the elapse of the predetermined time T from the rotation stop command time t1 of the electric compressor, the motor drive control device 4 displays the current information from the motor 2, Based on the voltage information, at least one value of the current value supplied immediately before the motor 2 is stopped or the rotational speed of the motor 2 immediately before the motor 2 is stopped is calculated, and the differential pressure is estimated based on the calculated value. .

  Then, since the estimated differential pressure P1 exceeds the predetermined pressure P2 at which the motor 2 can be activated at time t6, the motor drive control device 4 at time t7 when the estimated differential pressure becomes equal to or less than the predetermined pressure P2. Shifting to full braking control, the motor 2 is rotated forward at time t71. Therefore, the start failure of the motor 2 is eliminated.

  As described above, according to the electric compressor according to the first embodiment, the motor drive control device 4 performs zero vector energization or DC excitation energization intermittently by PWM control for a predetermined period after the motor stops, Reverse rotation relaxation control is performed so that the reverse rotation speed is less than the reverse rotation speed of the rotor generated by the differential pressure between the high-pressure refrigerant and the low-pressure refrigerant. The motor drive control device 4 rotates the motor 2 forward after performing zero vector energization control or full braking control of DC excitation energization when there is a restart request during reverse rotation mitigation control. It is possible to provide an electric compressor that can eliminate inertial energy due to rotation and suppress startup failure.

(Second Embodiment)
FIG. 5 shows the rotation speed of the compressor and the differential pressure between the discharge side and the suction side when the restart request is made after a lapse of a predetermined time since the rotation stop command of the electric compressor according to the second embodiment of the present invention. It is a figure which shows a time change.

  In the electric compressor of the second embodiment, after the motor drive control device 4 stops the motor 2, the reverse rotation speed is less than the reverse rotation speed of the rotor generated by the differential pressure between the high-pressure refrigerant and the low-pressure refrigerant. When the reverse rotation relaxation control is performed and there is a restart request during the reverse rotation relaxation control, the reverse rotation relaxation control is stopped or the full rotation control for reverse rotation of the motor is performed, and then the motor is rotated forward. It is characterized by making it.

  The operation of the electric compressor of the second embodiment will be described with reference to FIG. If there is a restart request at time t3 during the reverse rotation relaxation control, the motor drive control device 4 stops the reverse rotation relaxation control and reversely rotates the motor 2 (time t30 to t31). Rotate.

  Accordingly, it is possible to provide an electric compressor that can eliminate inertial energy due to reverse rotation of the motor 2 and suppress startup failure.

  Also, in the electric compressor of the second embodiment, when there is a restart request before a predetermined time has elapsed since the rotation stop command, the operation described in the electric compressor of the first embodiment shown in FIG. 4 is performed. You may make it do.

  That is, the motor drive control device 4 is based on the current information and voltage information from the motor 2 and at least one of the current value supplied immediately before the motor 2 stops or the rotational speed of the motor 2 immediately before the motor 2 stops. And the differential pressure is estimated based on the calculated value. When the restart request is made, the motor drive control device 4 shifts to the full braking control if the differential pressure is less than or equal to a predetermined pressure, and if the differential pressure exceeds the predetermined pressure, the differential pressure is set to the predetermined pressure. You may make it transfer to the said all brake control after becoming below.

1 Inverter
2 Motor 3 Compressor
4 Motor drive control device 5 Motor drive unit 12 Memory

Claims (6)

A compressor (3) having a rotor and compressing a low-pressure refrigerant into a high-pressure refrigerant by rotation of the rotor;
A motor (2) for driving the compressor (3);
A motor drive unit (5) connected to the motor (2) and having a plurality of switching elements;
A motor drive control device (4) for driving the motor (2) by on / off controlling the plurality of switching elements;
After the motor (2) is stopped, the motor drive control device (4) reverses so that the reverse rotation speed is less than the reverse rotation speed of the rotor generated by the differential pressure between the high-pressure refrigerant and the low-pressure refrigerant. Rotation mitigation control is performed, and when there is a restart request during reverse rotation mitigation control, all braking control for energizing all switching elements on the high side or low side of the motor drive unit (5) or one switching on the high side One of the three-phase high-side switching elements Uh, Vh, Wh and one of the three-phase low-side switching elements Ul, Vl, Wl; Or one of the high-side switching elements Uh, Vh, Wh for three phases and two of the low-side switching elements Ul, Vl, Wl for three phases. After the total braking control for energizing the door, an electric compressor, characterized in that forward rotation of the motor.   At the time of the restart request, the motor drive control device (4) shifts to the full braking control when the differential pressure is equal to or lower than a predetermined pressure, and when the differential pressure exceeds the predetermined pressure, the differential pressure is The electric compressor according to claim 1, wherein the electric brake is shifted to the full braking control after a predetermined pressure or less.   The motor drive control device (4) estimates the differential pressure based on at least one value of a current value supplied immediately before stopping the motor or a rotation speed of the motor immediately before stopping the motor. The electric compressor according to claim 1 or 2. A compressor (3) having a rotor and compressing a low-pressure refrigerant into a high-pressure refrigerant by rotation of the rotor;
A motor (2) for driving the compressor (3);
A motor drive unit (5) connected to the motor (2) and having a plurality of switching elements;
A motor drive control device (4) for driving the motor by turning on and off the plurality of switching elements;
After the motor is stopped, the motor drive control device (4) performs reverse rotation relaxation control so that the reverse rotation speed is less than the reverse rotation speed of the rotor generated by the differential pressure between the high-pressure refrigerant and the low-pressure refrigerant. When the restart request is made during the reverse rotation relaxation control, the motor is rotated forward after the reverse rotation relaxation control is stopped or the full opening control for reverse rotation of the motor is performed. compressor.   At the time of the restart request, the motor drive control device (4) shifts to the full release control when the differential pressure is equal to or lower than a predetermined pressure, and when the differential pressure exceeds the predetermined pressure, the differential pressure is The electric compressor according to claim 4, wherein the full-open control is performed after the pressure becomes equal to or lower than a predetermined pressure.   The motor drive control device (4) estimates the differential pressure based on at least one value of a current value supplied immediately before stopping the motor or a rotation speed of the motor immediately before stopping the motor. The electric compressor according to claim 4 or 5.

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