US-20260126044-A1 - SCROLL-TYPE ELECTRIC COMPRESSOR

US20260126044A1US 20260126044 A1US20260126044 A1US 20260126044A1US-20260126044-A1

Abstract

Provided is a scroll-type electric compressor capable of promptly decreasing pressure inside a scroll compression mechanism to smoothly and efficiently prevent reverse rotation and reduce noise when a motor is stopped. A control device 62 executes deceleration control of switching switching elements to decrease the rotation speed of a motor 2 after having received an instruction to stop the motor 2 , and brake control of stopping a rotor 29 of the motor 2 at an angle at which a back pressure hole of a movable scroll is not closed or an angle at which a discharge hole of a fixed scroll is not closed after the rotation speed of the motor 2 has been decreased by the deceleration control and switching the switching elements 66 A to 66 F to fix the rotor at the angle.

Inventors

Yuta Mochizuki
TOSHIHIRO KASAHARA
Takashi Kondo
Masayuki KIGURE

Assignees

SANDEN CORPORATION

Dates

Publication Date: 20260507
Application Date: 20230928
Priority Date: 20221021

Claims (6)

1 . A scroll-type electric compressor comprising: a scroll compression mechanism including a movable scroll having a back pressure hole and a fixed scroll to compress working fluid; a motor that drives the movable scroll; an inverter circuit including a plurality of switching elements to drive the motor; and a control device that switches the switching elements, wherein the control device executes deceleration control of switching the switching elements to decrease a rotation speed of the motor after having received an instruction to stop the motor, and brake control of stopping a rotor of the motor at an angle at which the back pressure hole of the movable scroll is not closed or an angle at which a discharge hole of the fixed scroll is not closed after the rotation speed of the motor has been decreased by the deceleration control and switching the switching elements to fix the rotor at the angle.
2 . The scroll-type electric compressor according to claim 1 , wherein the deceleration control executed by the control device includes sensorless deceleration control of decreasing the rotation speed of the motor by sensorless vector control after having received the instruction to stop the motor, and forced commutation deceleration control of decreasing the rotation speed of the motor to a predetermined low value by forced commutation control after the rotation speed of the motor has been decreased by the sensorless deceleration control.
3 . The scroll-type electric compressor according to claim 2 , wherein the control device controls a value of a phase current in the forced commutation deceleration control and/or the brake control based on a phase current in the sensorless deceleration control or a pressure of the scroll compression mechanism.
4 . The scroll-type electric compressor according to claim 1 , wherein the control device executes the brake control by electromagnetic braking before the rotation speed of the motor reaches zero, and feedback-controls a value of a phase current of the motor in the brake control.
5 . The scroll-type electric compressor according to claim 1 , wherein the control device detects the angle at which the back pressure hole or the discharge hole is not closed using at least one of a correlation between the phase current and the angle at which the back pressure hole or the discharge hole is not closed, a change in an amplitude of the phase current due to torque pulsation, a predetermined angle of the rotor, and a sensor that detects the angle of the rotor.
6 . The scroll-type electric compressor according to claim 1 , wherein the scroll compression mechanism includes the fixed scroll and the movable scroll in which spiral wraps are formed on respective faces of end plates so as to face each other, and compresses the working fluid by causing the movable scroll to revolve relative to the fixed scroll and moving a compression chamber formed between the wraps of the scrolls while narrowing the compression chamber from an outside to an inside, the discharge hole causes a discharge chamber on a back face side of the end plate of the fixed scroll and the compression chamber to communicate with each other, and the back pressure hole causes a back pressure chamber on a back face side of the end plate of the movable scroll and the compression chamber to communicate with each other, and the angle at which the back pressure hole is not closed is an angle at which the wrap of the fixed scroll does not close the back pressure hole of the movable scroll when the rotor is stopped, and the angle at which the discharge hole is not closed is an angle at which the wrap of the movable scroll does not close the discharge hole of the fixed scroll when the rotor is stopped.

Description

TECHNICAL FIELD The present invention relates to a scroll-type electric compressor, and more particularly to control for preventing reverse rotation of a scroll compression mechanism and a rotor. BACKGROUND ART A scroll-type electric compressor includes a scroll compression mechanism having a fixed scroll with a spiral wrap on a face of an end plate and a movable scroll with a spiral wrap on a face of an end plate. The scroll-type electric compressor is configured such that a compression chamber is formed between the wraps of the scrolls by making these wraps face each other and the movable scroll is revolved relative to the fixed scroll by a motor and is moved from the outside to the inside while the volume of the compression chamber decreases. In this manner, the scroll-type electric compressor compresses working fluid (refrigerant). In addition, the scroll-type electric compressor is integrally provided with an inverter device including a three-phase inverter circuit having a plurality of switching elements and a control device, and is driven by converting DC voltage from a DC power supply such as a battery into a three-phase AC voltage by switching the switching elements by the control device and applying the AC voltage to the motor. When receiving an instruction to stop the motor from the outside, the control device stops the switching operation of the switching elements, and stops driving the motor. At this time, as the working fluid (refrigerant) remaining in the compression chamber expands, the movable scroll (and the rotor of the motor) rotates reversely due to a differential pressure between the discharge side and suction side of the scroll compression mechanism, and noise is generated from the scroll compression mechanism. For this reason, there has also been developed a technique of fixing a rotor by brake control using power generation braking when a motor is stopped to prevent such reverse rotation (see, for example, Patent Literature 1). CITATION LIST Patent Literature Patent Literature 1: JP-A-2020-56322 SUMMARY OF INVENTION Problems to be Solved by Invention Here, FIG. 7 shows a sectional view of a movable scroll 100 and a fixed scroll 101 forming a general scroll compression mechanism. A wrap 103 is formed on a face of an end plate 102 of the movable scroll 100, and a wrap 106 is also formed on a face of an end plate 104 of the fixed scroll 101. A compression chamber 107 is formed between these wraps 103, 106. A back pressure hole 108 is formed in the end plate 102 of the movable scroll 100. The back pressure hole 108 is a hole causing a back pressure chamber 109 on the back face side of the end plate 102 and the compression chamber 107 to communicate with each other, and plays a role of releasing pressure to the compression chamber 107 with an intermediate pressure when the pressure (back pressure) in the back pressure chamber 109 becomes excessive. However, when the motor is stopped, if the wrap 106 of the fixed scroll 101 closes the back pressure hole 108 as shown in FIG. 7, the pressure (refrigerant and oil) in the compression chamber 107 cannot be released through the back pressure hole 108 to the back pressure chamber 109, which leads to a delay in the pressure release. For this reason, there is a risk that the pressure remains in the compression chamber 107 of the scroll compression mechanism at the end of the brake control and reverse rotation starts to generate noise. Thus, it is conceivable to extend the time for executing the brake control, but since power is distributed to the switching elements longer accordingly, problems such as failure and life shortening due to heat generation from the switching elements are caused this time. The present invention has been made in order to solve these conventional technical problems, and is intended to provide a scroll-type electric compressor capable of promptly decreasing pressure inside a scroll compression mechanism to smoothly and efficiently prevent reverse rotation and reduce noise when a motor is stopped. Solution to Problems The scroll-type electric compressor according to the present invention includes a scroll compression mechanism including a movable scroll having a back pressure hole and a fixed scroll to compress working fluid, a motor that drives the movable scroll, an inverter circuit including a plurality of switching elements to drive the motor, and a control device that switches the switching elements, and the control device executes deceleration control of switching the switching elements to decrease the rotation speed of the motor after having received an instruction to stop the motor, and brake control of stopping a rotor of the motor at an angle at which the back pressure hole of the movable scroll is not closed or an angle at which a discharge hole of the fixed scroll is not closed after the rotation speed of the motor has been decreased by the deceleration control and switching the switching elements to fix the rot