JPS63190594A - Motor operating method - Google Patents

Abstract

PURPOSE:To effectively attenuate the resonance noise of the carrier frequency of a stator and an inverter, by setting the carrier frequency of the inverter according to the outer diameter of a stator core. CONSTITUTION:A setting switch 17 sets the outer diameter of a stator core and the carrier frequency of an inverter at a variable control section 7 and transfers the carrier frequency set by the respective setting switches 17a-17c to the variable control section 7 with signal. An inverter section 6 changes a pulse waveform and outputs the carrier frequency to a compressor 3. By setting the carrier frequency with the dimension of the outer diameter of the stator core in this manner, resonance noise is attenuated, and a noise level is effectively lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of operating an electric motor used in a refrigeration cycle or the like.

Conventional technology In recent years, inverter devices for electric motors used in refrigeration cycle equipment have changed from variable carrier frequency to carrier frequency - from the viewpoint of energy saving, space saving, and noise reduction.
It is transitioning to the Hoto style.

These electric motor inverter devices generate an approximate sinusoidal voltage with a pulse voltage waveform to drive the compressor.

In addition, this pulse voltage waveform is calculated and output by a microcomputer, and the carrier frequency is always constant even if the rotation frequency is varied from 01 to 1801. By dividing the pulse voltage waveform into small pieces, it can be more closely approximated to a sine wave voltage waveform. This improves inverter efficiency.

A conventional electric motor inverter device as described above will be described below with reference to the drawings.

FIG. 6 shows a block diagram of a conventional electric motor inverter device.

Reference numeral 1 denotes a power source, and the compressor 3 is driven by an inverter device 2 from the power source 1 at variable speed by controlling voltage, current, and rotational frequency. In the inverter device 2, the converter section 4 from the power supply 1 converts alternating current into direct current, and after smoothing the direct current with a smoothing circuit section 6, the inverter section 6 inversely converts the direct current into alternating current with variable frequency. 7
is a variable control section that controls voltage, current, and rotation frequency. The variable control section 7 generates an approximate sine wave voltage with a pulse voltage waveform, and still generates an inverter carrier frequency that is the number of the pulse voltage waveform.

FIG. 5 shows a compressor 3 driven by the conventional electric motor inverter shown in the block diagram of FIG. In FIG. 6, reference numeral 8 denotes a sealed case in which a motor section 11 consisting of a stator 9 and a rotor 10 is located.
There is a compression element section 13 that connects the crankshaft 12 from the electric motor section 11 and is a mechanism for compressing refrigerant gas. 14
is a block that fixes the compression element section 13 to the sealed case 8. 15 is a discharge pipe for discharging compressed refrigerant gas, and 16 is a suction pipe for sucking refrigerant gas.

The electric motor inverter device 2 drives the compressor 3.

FIG. 4 shows a 1-1' cross section in FIG. 6. In FIG. 4, T represents the outer diameter of the stator core of the stator 9. This stator core outer diameter T determines the natural frequency. FIG. 2 is a graph showing the relationship between the stator core outer diameter T and the natural frequency determined by the modal analysis device. The vertical axis represents the stator core outer diameter T, and the horizontal axis represents the natural frequency. The stator natural vibration curve is shown in the same graph.

The operation of the electric motor inverter device configured as above will be described below.

First, a waveform similar to a sine wave outputted by the inverter device 2 is transmitted to the electric motor section 11, and the electromagnetic force generated between the stator 9 and the rotor 1o rotates the rotor 1o, which is then compressed by the crankshaft 12. The refrigerant gas is transmitted to the element section 13 and compressed.

By the way, the rotational frequency range of the compressor is oH, ~180
It is a circle, the rotation frequency is f, and the carrier frequency of the inverter is 4. The frequency F of the sound generated by the inverter carrier frequency Ka is determined by the following equation.

F=2Ka±2f ・Old ・Seal ・Old ・(1
) Therefore, when the conventional stator core outer diameter T = 169 mm and the carrier frequency = 1100 mm, the frequency F at which noise is generated has a variable range of 1840 mm to 25 Hz, intersects the stator natural vibration curve, and reaches the resonance point. C exists. As a result, the stator 9 resonates and resonance noise is generated. Problems to be solved by the invention However, in the above configuration, the inverter efficiency is improved by keeping the carrier frequency constant; however, (1)
From the formula, stator core outer diameter T is 16911111,
This has the disadvantage that resonance occurs due to the carrier frequency of the inverter, increasing the noise level of the compressor.

In view of the above drawbacks, the present invention provides an electric motor operating method that reduces resonance noise by setting an inverter carrier frequency that avoids resonance with respect to the stator core outer diameter.

Means for Solving the Problems To achieve this objective, the present invention provides 30) b to 1801
The inverter carrier frequency is set so that resonance does not occur due to the inverter carrier frequency at all rotational frequencies f of h.

Function: This configuration prevents resonance due to the carrier frequency of the inverter and provides an extremely effective noise reduction effect.

EXAMPLE An example of the present invention will be described below with reference to the drawings. In order to avoid duplication of explanation, the same parts as in the conventional example are given the same reference numerals and the explanation will be omitted.

1 to 5 show an embodiment of an inverter device for an electric motor according to the present invention. In FIG. 3, reference numeral 17 is a setting switch for setting the stator core outer diameter T and the inverter carrier frequency Kb in the variable control section 7. Here, the stator core outer diameter T is set at intervals of 50+m and the carrier frequency Kb of the inverter is set as shown in the table below.

17a to 17C are switches for each setting.

In FIG. 2, the shaded area d is the frequency range of the sound F generated by the carrier frequency of the inverter, and this exists within each range of the stator core outer diameter T in which the resonance point C does not exist. Also, in FIG. 1, the operation of the setting switch 17 is shown in a flowchart in G.
8 to 27 are each step.

The operation of the electric motor inverter device configured as described above will be explained below.When the power is turned on at the 0 setting switch 17, steps 18 and 19 are started, and steps 17 and 17 are started.
When switch a is input, Yes is selected in step 20.
, go from step 21 to 26, and END at 27
do. When switch 17b is selected, steps 22 to 23, 26, and 2a are activated. If switch 17c is selected, steps 24, 25, 26, and 27 are activated.

The carrier frequency set by this switch is transmitted as a signal to the variable control section 7, the pulse waveform is changed by the inverter section 6, and the carrier frequency K is output to the compressor 3.

Therefore, in the rotational frequency 01~1801-1x equation (1), if we replace the inverter carrier frequency Ka with the inverter carrier frequency Kb and calculate the frequency F of the sound generated by the inverter carrier frequency Kb, the point on the stator natural vibration curve I never take it. From this, there is no point that resonates due to the carrier frequency Kb of the inverter. Therefore, the resonant sound of the stator 9 is
The noise level of the compressor 3 can be reduced very effectively.

As described above, according to this embodiment, by setting the carrier frequency based on the stator core outer diameter dimension, resonance sound can be extinguished and the noise level can be effectively reduced.

Furthermore, by setting the set value of the carrier frequency to a higher value, the inverter efficiency can be improved, which is effective.

According to this embodiment, the rotational frequency is varied from 01-II to 1000, and the same effect can be obtained at all rotational frequencies within this range.

Effects of the Invention As described above, the present invention sets the carrier frequency of the inverter according to the outer diameter of the stator core, thereby extremely efficiently connecting the stator without reducing inverter efficiency and without changing the specifications of the stator. It can effectively reduce the resonance sound of the carrier frequency of the inverter, and its practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of a setting switch according to an embodiment of the present invention, FIG. 2 is a graph showing natural frequency characteristics with respect to the outer diameter of the stator core, and FIG. 3 is a block diagram of an inverter device of the electric motor. Figure 4 is a sectional view taken along line I-1' in Figure 6 of the same compressor;
The figure is a longitudinal sectional view of the same compressor, and FIG. 6 is a block diagram of a conventional inverter device for an electric motor. 2... Inverter device, 3... Compressor, 8... Sealed case, 9... Stator, 10... Rotor, 11... ...Electric motor part, 12...Crankshaft, 13...
・Compression element part, 14...Block, K...
... Inverter carrier frequency, T ... Stator core outer diameter. Name of agent: Patent attorney Toshio Nakao and one other person II
Fig. 2 Stator core diameter cutting 1 Rogaku suction bamboo no. 3 Shoulder flame first ridge (KHz) /7b 8-Capacity case 9-Stator 10-TJ-Ri/2--Crank lift No. 4 Figure 8 - Secret case q - Stator 10 - Rotor / I - Single blade vortex / 4 - 70 - l δ Figure 6 L ++ J

Claims (1)

[Claims] The motor includes a cylindrical sealed case, an electric motor section consisting of a stator and a rotor disposed in the sealed case, a compression element part continuous with the rotor and a crankshaft, and a block for fixing the compression element part. By driving the compressor, generating an approximate sinusoidal voltage with a pulse voltage waveform, and setting the carrier frequency of the inverter, which is the number of the pulse voltage waveforms, with respect to the outer diameter of the stator core, resonance can be avoided. A method of operating an electric motor operated at the carrier frequency of an inverter.