JP3034734B2 - Vibration compressor power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for a vibration-type compressor, and more particularly, to a power supply for a vibration-type compressor having two switching elements and supplying power to the vibration-type compressor by switching alternately. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device of a vibration type compressor that generates an AC voltage that follows a resonance frequency of the vibration type compressor.

[0002]

2. Description of the Related Art In a conventional power supply device of a vibration-type compressor using a DC power supply, for example, a battery as a driving source, the resonance frequency of the vibration-type compressor is predetermined in terms of structure. A voltage was generated, and an AC voltage at that frequency was supplied to the vibrating compressor.

[0003]

Since the resonance frequency of the vibration-type compressor changes due to load fluctuations, the efficiency of the vibration-type compressor would be increased if the power supply frequency supplied to the vibration-type compressor was kept constant as in the prior art. There were bad drawbacks.

In particular, when a battery is used as a driving source, an efficient driving method is desired. SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and in a power supply device of a vibration type compressor including two switching elements and configured to alternately switch to supply power to the vibration type compressor, An object of the present invention is to provide a power supply device of a vibration type compressor that is driven by an AC power supply having a frequency that follows a resonance frequency of the compressor.

The applicant of the present invention has proposed that the vibration type compressor is always operated under optimum conditions by matching the vibration period of the electric vibration system in the vibration type compressor with the natural vibration period of the mechanical vibration system. An application that can be driven has been filed.
173676).

It has also been found that the efficiency is maximized when the difference between the first half and the second half of the current waveform has a certain value. According to the present invention, the electric condition is grasped as the average value or the integral value of the current of the vibrating compressor flowing through the current detecting means, and the automatic follow-up control is performed.

[0007]

In order to solve the above-mentioned object, a power supply device for a vibrating compressor according to the present invention comprises two switching elements, and an inverter circuit for converting DC to AC by alternately switching the switching elements. And a polarity inversion circuit for generating a DC voltage -E whose polarity is inverted based on the DC voltage E, and a control unit for controlling the inverter circuit unit. A shunt resistor for detecting a current flowing through the compressor, and an oscillator for oscillating a pulse whose oscillation frequency is variable, and an oscillation frequency of the oscillator being halved.
And a frequency divider for dividing the frequency by 2
A switching element control circuit for alternately switching the switching elements, and a current value flowing through the shunt resistor corresponding to a half cycle of the oscillation frequency based on the oscillation frequency of the oscillator. A frequency tracking circuit for variably controlling the oscillation frequency of the oscillator so that the oscillation frequency becomes a given value.

[0008] When comparing the current values flowing through the shunt resistor with respect to each half cycle of one cycle of the oscillation frequency based on the oscillation frequency of the oscillator, an average value averaging the current value flowing through the shunt resistor is used. A shunt resistor, and a current flowing through the shunt resistor is compared by an average value, or an integrating circuit that integrates a current value flowing through the shunt resistor is provided, and the current flowing through the shunt resistor is compared by an integrated value. ing.

[0009]

The vibration compressor can be driven by an AC power supply having a resonance frequency of the vibration compressor, thereby improving the efficiency of the vibration compressor.

[0010]

FIG. 1 shows an embodiment of a power supply unit for a vibration type compressor according to the present invention. In the figure, 1 is a vibration compressor, 2 is a battery, 3 is a polarity inversion circuit, 4 is a first transistor, 5 is a second transistor, 6 is an inverter circuit section, 7 is a control section, and 8 is AC-DC. A converter, 9 is an automatic switch, 10 is a commercial AC power supply, 11 is a transistor, 12
Is a pulse generating circuit, 13 is a choke coil, 14 is a diode, 15 is a capacitor, 16 and 17 are terminals, 18 is a relay coil, 19 is a relay contact, 20 is a shunt resistor, 21 is an oscillator, 22 is a frequency divider, 23 Denotes a transistor control circuit, and 24 denotes a frequency tracking circuit.

FIG. 1 shows a power supply unit of an AC / DC type vibratory compressor. The vibrating compressor 1 is a refrigerator compressor that operates on a low AC voltage, for example, a 12 V system or a 24 V system.

The battery 2 is a DC power supply mounted on an automobile and has a voltage of 12 V or 24 V, and serves as a power supply of the vibration compressor 1 while the automobile is moving. The polarity inversion circuit 3 includes a transistor 11, a pulse generation circuit 12, a choke coil 13, a diode 14, and a capacitor 15, and is a circuit that generates a DC voltage -E having a polarity opposite to the DC voltage E with respect to the ground.

More specifically, referring to FIG. 3, for example, a pulse generating circuit 12 using an astable multivibrator circuit or the like outputs a control signal for turning on / off the transistor 11 and generates the pulse (I) in FIG. Since this pulse is applied to the choke coil 13, a voltage waveform having positive and negative directions shown in (II) of FIG. 3 is generated at both ends of the choke coil 13. Of the positive and negative voltage waveforms, the shaded negative voltage passes through the diode 14 and
The capacitor 15 is charged in the form of a negative voltage shown in (III). Accordingly, a DC voltage -E having a polarity substantially inverted with respect to the DC voltage E of the battery 2 is generated at the output terminal X of the polarity inversion circuit 3.

The inverter circuit section 6 includes a first transistor 4 and a second transistor 5, and the first transistor 4 and the second transistor 5 are turned on alternately to generate an AC voltage. , To supply the AC voltage to the vibrating compressor 1.

The control section 7 is a circuit for outputting a control signal for controlling the first transistor 4 and the second transistor 5 to be turned on alternately as described above. The control unit 7
For example, the first transistor 4 and the second
The control is performed such that the duty ratio of each main waveform of the transistor 5 is changed and the AC voltage output from the inverter circuit unit 6 is substantially varied to change the frequency applied to the vibration compressor 1.

The AC-DC converter 8 is used when the vibration type compressor 1 is driven by the commercial AC power supply 10,
It converts the AC voltage of the commercial AC power supply 10 into a DC voltage having the same potential as the DC voltage of the battery 2.

The automatic switch 9 has a commercial AC power supply 10
7, the DC power supply of the AC-DC converter 8 is connected in preference to the DC power supply of the battery 2 side. The shunt resistor 20 detects a current flowing through the vibration type compressor 1, and in the case of FIG.
, The current flowing through the vibration type compressor 1 when driven by the negative DC voltage −E whose polarity is inverted is detected.

The oscillator 21 is a pulse generator whose oscillation frequency can be varied. The frequency divider 22 is a circuit that divides the frequency of the pulse generated by the oscillator 21 into half.

The transistor control circuit 23 is a driver that turns on the first transistor 4 and the second transistor 5 alternately with a pulse having a frequency divided by the frequency divider 22.

The frequency tracking circuit 24 compares the values of the currents flowing through the shunt resistor 20 with respect to each half cycle of one cycle of the oscillation frequency generated by the oscillator 21, and sets the difference between the oscillators 21 to a predetermined value. This is a circuit for outputting a control signal for variably controlling the oscillation frequency of the control signal.

The power supply device of the vibration type compressor having such a configuration will be described as driving a refrigerator mounted on an automobile or the like, or a refrigerator in which the container itself is a refrigerator.

While the refrigerator is moving, DC power of a battery 2 mounted on an automobile or the like is supplied to the vibrating compressor 1 via an automatic switch 9. That is, the DC voltage of the battery 2, for example, 12 V, is input to the polarity inversion circuit 3 via the automatic switch 9, and −12 V is generated at the output terminal X of the polarity inversion circuit 3 as described above. The first transistor 4 and the second transistor 5 in the inverter circuit unit 6 are alternately turned on by a control signal output from the control unit 7, and the vibration type compressor 1 is based on the operation of the first transistor 4 A voltage of 12 V from zero potential and a half-period of zero potential are applied, and then a voltage of -12 V from zero potential based on the operation of the second transistor 5 and a half-period of zero potential are applied. The AC voltage having one cycle of positive and negative is applied.

That is, a so-called single-end push-pull (SEPP) circuit is constituted by the first transistor 4, the second transistor 5, and the control unit 7 with the vibration type compressor 1 as a load. An alternating voltage having positive and negative values centered at zero potential is applied. Therefore, one end of the vibration-type compressor 1 can be grounded, and the cord can be connected to the case itself of the vibration-type compressor 1 as shown in FIG. Is also simplified.

In the control unit 7, the frequency follow-up circuit 24 compares the average values of the currents flowing through the shunt resistor 20 in correspondence with half of one cycle of the oscillation frequency generated from the oscillator 21, and the difference is predetermined. It outputs a control signal for variably controlling the oscillation frequency of the oscillator 21 so that the oscillation frequency becomes equal to the calculated value. Accordingly, since a pulse having a frequency corresponding to the control signal is oscillated from the oscillator 21, an AC voltage having a frequency that follows a change in the resonance frequency due to a load change of the vibration compressor 1 can be generated.
The vibration type compressor 1 can be driven in the most efficient state.

When the vehicle arrives at a stop or the like and the commercial AC power supply 10 is connected to the terminal 17, the AC-DC converter 8 outputs 12 V having the same potential as the DC voltage of the battery 2. The DC voltage of 12 V from the AC-DC converter 8 energizes the relay coil 18 and causes the relay contact 19 to contact the AC-DC converter.
Switch to DC converter 8 side. This commercial AC power supply 10
Operates in exactly the same manner as in the case of the battery 2 described above, and the alternating-current voltage having positive and negative values centered on zero potential is applied to the vibration compressor 1.

FIG. 2 shows an embodiment of a specific circuit of the power supply device of the vibration type compressor according to the present invention. In the figure,
1, 2, 4 to 7, 20 to 24 correspond to those in FIG. 1, 31 is an arithmetic circuit, 32 and 33 are averaging circuits, 3
4, 35 are analog switches, 36 is an inverter circuit,
37 denotes an amplifier, 38 denotes a DC power supply, 39 and 40 denote capacitors, and 41 and 42 denote resistors.

In FIG. 2, the shunt resistor 20
Is configured to detect a current flowing through the vibration-type compressor 1 when a DC voltage 12 V of the battery 2 is applied to the vibration-type compressor 1, and the DC power supply 38 is connected to the polarity inversion circuit 3 of FIG. Yes, it is. And the first transistor 4
An FET transistor is used as the second transistor 5.

The operation of FIG. 2 will be described with reference to the operation waveform diagram of FIG. The oscillator 21 is set so as to oscillate a frequency of a 100 Hz pulse, which is twice the resonance frequency of the 50 Hz, when the resonance frequency in the design of the vibration compressor 1 is 50 Hz, for example (FIG. 4). A).

The oscillator 21 can vary its oscillation frequency of 100 Hz as described above.
1 and the capacitance C of the capacitor 39 connected to the oscillator 1
The oscillation frequency of 100 Hz is determined by a time constant CR with respect to the resistor R when the resistor 41 is viewed from 1.

The flip-flop circuit of the frequency divider 22 divides the oscillation frequency 100 Hz of the oscillator 21 by half, and its output Q and Q bar pass through each driver of the transistor control circuit 23. Thus, the first transistor 4 and the second transistor 5 in the inverter circuit section 6 composed of FET transistors are alternately turned on.

Now, focusing on the first transistor 4,
When the first transistor 4 is controlled to be turned on (B in FIG. 4), the current flowing through the vibrating compressor 1 is detected by the shunt resistor 20 (C in FIG. 4).

On the other hand, the 100 Hz pulse generated from the oscillator 21 is supplied to the analog switch 34 and the inverter circuit 3.
6, the analog switch 35 is controlled to be turned on, so that the current flowing through the vibrating compressor 1 detected by the shunt resistor 20 is divided into two by the analog switch 34 and the analog switch 35. 4 are input to the averaging circuits 32 and 33, respectively.

The respective current waveforms input to the averaging circuits 32 and 33 are averaged and input to the arithmetic circuit 31. In the arithmetic circuit 31, the difference between the average values of the two current waveforms input to the arithmetic circuit 31 is a predetermined value based on one of the average values of the current waveforms input to the averaging circuit 32, for example. Is output to charge the capacitor 40.

It is now assumed that the amount of charge of the capacitor 40 by the control signal from the arithmetic circuit 31 is small,
When the voltage at the connection point Y between 0 and the resistor 42 decreases, the time constant CR described above changes. Accordingly, the oscillation frequency generated from the oscillator 21 increases accordingly, and a control signal is output such that the difference between the average values of the two current waveforms input to the arithmetic circuit 31 becomes a predetermined value, thereby stabilizing. I do. That is, it follows the resonance frequency of the vibration type compressor 1. Conversely, when the voltage at the connection point Y increases, the oscillation frequency generated from the oscillator 21 decreases, and control is performed so as to match the resonance frequency of the vibration compressor 1.

In this way, a pulse having a frequency following the resonance frequency of the vibration type compressor 1 is generated from the oscillator 21,
The first transistor 4 and the second transistor 5 in the inverter circuit section 6 configured by FET transistors are alternately turned on through the respective drivers of the frequency divider 22 and the transistor control circuit 23. Therefore, the vibration type compressor 1 can be driven with maximum efficiency even with respect to the load fluctuation of the vibration type compressor 1.

It is to be noted that an integrating circuit is used in place of the averaging circuits 32 and 33 in FIG. A similar result can be obtained even if the difference between the integral values of the two current waveforms input to the first and second waveforms is set to a predetermined value. As the current detecting means, in addition to the shunt resistance, a current transformer using a Hall element, a resistance V _DS between the drain and source of the FET, a method using a fuse, and the like are used.

[0037]

As described above, according to the present invention, the vibration type compressor can be driven with maximum efficiency even when the load of the vibration type compressor changes.

[Brief description of the drawings]

FIG. 1 is a configuration of an embodiment of a power supply device of a vibration type compressor according to the present invention.

FIG. 2 shows an embodiment of a specific circuit of a power supply device of the vibration type compressor according to the present invention.

FIG. 3 is an explanatory diagram of operation waveforms of a polarity inversion circuit.

FIG. 4 is an operation waveform diagram of the embodiment of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration compressor 2 Battery 3 Polarity inversion circuit 4 1st transistor 5 2nd transistor 6 Inverter circuit part 7 Control part 20 Shunt resistor 21 Oscillator 22 Divider 23 Transistor control circuit 24 Frequency tracking circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 7/48 F04B 35/04 F25B 1/02 H02P 7/00 101 H02P 7/63 302

Claims (3)

(57) [Claims] An inverter circuit comprising two switching elements for converting a direct current into an alternating current by alternately switching the same, a polarity inverting circuit for generating a DC voltage -E whose polarity is inverted based on the DC voltage E, A power supply device for a vibration-type compressor, comprising: a control unit for controlling the inverter circuit unit; and a current detection unit for detecting a current flowing through the vibration-type compressor. An oscillator that oscillates pulses that can be varied, a frequency divider that divides the oscillation frequency of the oscillator by half, and switching that alternately switches the two switching elements at the frequency that the divider divides Based on the oscillation frequency of the oscillator and the element control circuit, the values of the currents flowing through the current detection means are compared with each other in a half cycle corresponding to one cycle of the oscillation frequency. And a frequency tracking circuit that variably controls the oscillation frequency of the oscillator so that the difference becomes a predetermined value, thereby improving the efficiency of the vibration compressor and controlling the amplitude of the vibration compressor. Power supply for vibration compressor. 2. The frequency tracking circuit according to claim 1, further comprising an averaging circuit for averaging a current value flowing through said current detecting means, and comparing the current flowing through said current detecting means with an average value. The power supply device for a vibration type compressor according to claim 1. 3. The frequency tracking circuit according to claim 1, further comprising an integrating circuit for integrating a value of the current flowing through the current detecting means, wherein the current flowing through the current detecting means is compared with the integrated value. 2. A power supply device for the vibration-type compressor according to 1.