JPH0938525A - Control device for motor for centrifugal machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the leakage of current generated by the on/off operation of power switching elements, and prevent the generation of noises transmitted to an alternating current power line by setting an insulation transformer between an alternating current power source and a voltage convertor and providing a filter circuit between the power convertor and the insulating transformer. SOLUTION: A control device of a motor for a centrifugal machine is so acuated as to lower the content of a harmonic component of current passing through an alternating current power source 21, and one end of the control device is connected to the alternating current power source 22, while a power convertor 22 is provided on the other end. An insulating transformer 59 is provided between the alternating current power source 21 and the power convertor 22, and a filter circuit 70 formed by connecting bypass condensers 65 and 66 with choke coils 63 and 64 and also insulating ends between the power convertor, 22 and the insulating transformer 59. The leakage of current is less prone to flow in the control device by interposing the insulating transformer 59 as above-mentioned, and a part of the leakage of current is branched by the filter circuit 70 to reduce the high-currency current, and also the leakage of current is controlled by the whole of the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifuge in which a motor for rotating a rotor is controlled by an inverter, and more particularly to a centrifuge motor capable of reducing a leakage current generated by a high frequency current output from the inverter or the like. The present invention relates to a control device.

[0002]

2. Description of the Related Art A conventional motor control device for a centrifuge is disclosed, for example, in Japanese Patent Application No. 06-038474 and Japanese Patent Application No. 06-049204 filed by the applicant of the present application. A choke coil for removing harmonic components, a field effect transistor, a gate turn-off thyristor, a power switching element such as iGBT, and a step-up converter composed of a smoothing capacitor, and the current flowing to an AC power supply are almost SiN waves. Further, the inverter performs v / f control of the high frequency induction motor by PWM control of the power switching element with respect to the high voltage energy stored in the smoothing capacitor, and controls the rotation speed of the rotor.

[0003]

However, in such a conventional control device, by the operation of the step-up converter by the on / off operation of the power switching element and the operation of the PWM control inverter using the high-voltage smoothing capacitor as a power source, A high-frequency current flows through the power control circuit, and a leakage current is generated through the floating capacitor that exists between the current path and the casing of the centrifuge, which may exceed the regulation value specified by the Pharmaceutical Affairs Law. If the grounding is insufficient or the grounding impedance is high, there is a problem that an electric potential difference is generated between the grounding and the centrifuge housing, and the operator receives an electric shock.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and provide a control device for a centrifuge in which the generation of leakage current is reduced.

[0005]

The above-mentioned object is to control the content of the harmonic component of the electric current that is systemically connected to the AC power supply and passes through the AC power supply with the motor such as the induction motor or the AC servomotor that rotationally drives the rotor. A power converter that operates so as to decrease, one of which is connected to an AC power supply and the other of which is an output of DC power, and the motor drive inverter connected between the DC output end of the power converter and the motor, etc. In the device including the driver device, an insulating transformer is provided between the AC power source and the power converter, and a choke coil is provided between the power converter and the insulating transformer, and a bypass capacitor is provided between the choke coil and ground. This is achieved by providing a filter circuit formed by connecting

[0006]

It has been found that by configuring the motor control device for the centrifuge as described above, the leakage current flowing through the casing of the centrifuge can be greatly reduced. By interposing an insulation transformer, it becomes difficult for a leakage current in the form of a so-called common mode current component to flow to the control device for the centrifuge motor, but in this state it is insufficient to reduce the leakage current value. Leakage current still flows through the primary and secondary windings of the isolation transformer and ground. Therefore, the high-frequency current returning to the secondary winding of the isolation transformer is made to partially flow by the filter circuit including the common mode choke and the vice-pass capacitor, and the high-frequency current flowing through the winding of the isolation transformer is reduced. The control device for the machine motor operates so as to suppress the leakage current.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described in detail below with reference to the drawings. First, in FIG. 2 showing a block diagram of a control device for a centrifuge motor, which is suitable for application of the present invention, in FIG.
1 is an AC power supply, 22 is an AC side connected to an AC power supply 21 via a reactor 23, and a DC side is a smoothing capacitor 2
A power supply which is a power converter having a step-up / down converter function in which a switching element such as a bipolar transistor IGBT or FET is connected in reverse parallel to each of the rectifying elements constituting the reflux rectifying circuit to the reflux rectifying circuit connected to 4. Is a bidirectional power converter for use, and 25 is a switching element serving as an AC phase control element such as a triac or a thyristor for adjusting the charging voltage of the smoothing capacitor connected between the reactor 23 and the smoothing capacitor by phase control. Reference numeral 26 denotes a reflux rectifier circuit whose AC side is connected to a motor 28 that drives a centrifugal separation rotor 27 such as an induction motor, and whose DC side is connected to a smoothing capacitor 24. Inverter device function in which a switching element of the same type as the bidirectional power converter for power supply 22 is connected to the rectifying element A motor for bidirectional power converter 26 as a motor driver for driving devices with. In the PWM control inverter control of the switching element of the motor bidirectional power converter 26, 29 is a ROM which stores the ON / OFF pulse pattern for the PWM control of the switching element, and the data output of the ROM 29 The logical value of "1" or "0" of the output data of the line is a pulse pattern, and these data are sequentially read by the output of the counter 30 connected to the address line, and the clock of the counter 30 is the oscillator. PLL
It is applied by the clock output of the pulse generator 31, and the clock output frequency of the PLL pulse generator 31 is controlled by the timer LSI 32. Reference numeral 33 is a latch that prevents time irregularity of data read from the ROM 29 and synchronizes it. Reference numeral 34 is a gate driver that drives the photocoupler 35 in accordance with the output logic of the latch 33. ON / OFF of six switching elements of the bidirectional power converter 26 for motors is controlled, and the motor 28 is PWM-controlled by the bidirectional power converter 26 for motors. The anode control line of the smoothing capacitor 24 is indicated by 24a, and the cathode side line is indicated by 24b. In controlling the switching elements of the bidirectional power converter 22 for power supply, 36 is, for example, an FA5331 type power factor correction control I manufactured by Fuji Electric Co., Ltd.
The pulse width control output of this IC is amplified by the gate driver 38 via the pattern switch 37 and drives the photocoupler 39. The signal output of the photocoupler 39 controls ON / OFF of the four switching elements of the power bidirectional power converter 22. The power factor correction control IC 36 is a current in which the power-source phase-direction power converter 22 cooperates with the reactor 23 and has a low harmonic current content similar to the voltage waveform of the AC power source 21, and is smoothed during the power running of the motor 28. Insulation transformer, etc. to enable forward operation which becomes a step-up converter which charges the capacitor 24 to a constant voltage and reverse operation which becomes a step-down converter which discharges the smoothing capacitor 24 and maintains a constant voltage during regeneration of the motor 28. For smoothing the power supply voltage waveform by the V sensor 40 according to the above, the power supply current waveform by the I sensor 41 such as the hall current sensor, and the CV sensor 42 by the combination of the VF and FV converters insulated by, for example, a photocoupler. The charging voltage signal of the capacitor 24 is input as a sensor input signal. Reference numeral 43 is an analog switch, which is used for the forward operation of the bidirectional power converter 22 for power supply,
The signal output of the I-sensor 41 is the attenuator 4 so that the reverse operation can be performed by the same control action of the power factor correction control IC.
The signal level can be switched by 4 and the CV sensor 4
The signal output of 2 is provided by the differential amplifier 45 so that it can be switched and selected from the subtraction signal based on the reference voltage source 46, and the signal output of the I / OLSI 47 interlocks with the pattern switch 37. Then, switching is performed. 48
Is a positive / negative cycle detector of the power supply which detects the positive / negative cycle state of the AC power supply 21 and outputs a logic signal to the pattern switch 37, and 49 is the I / O LS of the signal output.
A 0-cross circuit that outputs a 0-cross signal of the AC power supply 21 for the phase control of the AC phase control element 25 that outputs to I47, and 51 represents a reference clock of the PLL pulse generator 31 or the like that outputs the signal output to the timer LSI 32. This is the source oscillator. The AC phase control element 25 is controlled by the signal output of the timer LSI 32 via the photo coupler 50. The power supply control circuit 52 is a circuit that supplies drive power to the gate drivers 34 and 38, and when an overcurrent of the bidirectional power converters 22 and 26 or an abnormality such as an arm short circuit occurs, or after the AC power supply 21 is turned on. The bidirectional power converter 2 is used until the preparation of the operation of the entire control device is completed and when the control state is switched during other operation.
It is provided to prevent an ON signal from being applied to the switching elements 2 and 26. Reference numeral 53 is a rotation sensor for detecting the rotation speed of the rotor 27, 54 is a counter circuit for measuring the rotation speed of the rotor 27, and 55 is a timer LS.
This is a centrifuge control CPU that controls the I32, I / O LSI 47, and the counter circuit 54. Bidirectional power converter 2
Reference numeral 100 denotes a control means for performing on / off control of the switching elements 2 and 26.

As described above, the V sensor 40, the I sensor 41, the CV sensor 42, the photocouplers 35, 39, 5
By the insulation signal transmission means of 0, the insulation of the reference voltage is achieved between the bidirectional power converters 22 and 26, which are power circuits, and the control means 100, and the AC phase control element 25 or the bidirectional power converter 22. , 26 to prevent the control means 100 from being affected by malfunctions and the like due to noise generated by the high-speed switching operation of the switching elements in 26.

With regard to the details of the operation of the present invention having the above-mentioned configuration, Japanese Patent Application No. 06-04920 filed by the applicant of the present application
Similar to No. 4, in the control device having the above-mentioned configuration, the power switching elements of the power bidirectional power converter 22 and the motor bidirectional power converter 26 perform on / off operations. The bidirectional power converter 22 performs a step-up converter operation corresponding to the power running operation of the motor 28 by the motor bidirectional power converter 26 or a step-down converter operation corresponding to the regenerative operation of the motor 28, while the smoothing capacitor 24 is turned on. Bidirectional power converter for motor 26 used as power source
Is formed by the reactor 23, the winding of the motor 28, and the like by the PWM control inverter operation for the power running and regenerative operation of the motor 28, causing a high-frequency current to flow in the power control circuit due to the on / off operation of the power switching element. Leakage current flows between the current path and the casing of the centrifuge through the floating capacitor. Therefore, in order to suppress the above leakage current, an electric component having the configuration shown in FIG. 1 showing the embodiment of the present invention is connected between the AC power supply 21 and the reactor 23 in FIG.

In FIG. 1, the parts having the same functions as those in FIG. 2 are designated by the same reference numerals, 56 is a line filter for noise prevention, 57 is a lightning surge absorber, and 58 is a no-fuse breaker. And 59 is an insulating transformer. The isolation transformer 59 is d, with respect to the reference tap C, as shown in the figure.
e, f, g, h voltage switching taps, and a tap i on the secondary side, which is equal to the voltage between cd on the primary side and insulated from the primary side.
-J is provided, and the hot line side reactor 23a and the dead line side reactor 23b of the reactor 23 are connected to the taps i-j, respectively. Between the voltage taps c and d on the primary side, a vacuum pump 60, a diffusion pump 61, which serves as an auxiliary device of the centrifuge, and a control unit 10.
A switching power supply for supplying a stabilizing voltage for control such as 5 V, +12 V, and -12 V to 0, a cooling fan 62, and other coolers necessary for operating the centrifuge are connected. A low frequency common mode choke coil 63 and a high frequency common mode choke coil 64 are provided between the secondary side i-j tap of the isolation transformer and the reactors 23a and 23b.
And bypass capacitors 65 and 66 are connected in series at the connection ends of the choke coils 63 and 64,
The common connection end of 66 is connected to ground 67, and these components form a filter circuit 70. Due to the presence of the filter circuit 70, the noise terminal voltage sent to the AC power supply 21 is reduced, and further, an across-the-line capacitor 68 is connected to the connection ends of the choke coil 64 and the reactors 23a and 23b. A snubber circuit 69 in which a capacitor and a resistor are connected in series is connected in parallel to the switching element 25, and a leakage current control effect described in detail below is exhibited.

FIG. 3 shows an example of measuring the degree of suppression of the leakage current of the control device for the centrifuge motor having the above structure.
In the figure, the upper graph shows the number of rotations of the rotor 27 corresponding to the operation modes I to VI, and the lower graph corresponds to each operation mode I to VI of the upper graph, and is measured. The leakage current value is displayed as a line graph.
The connection conditions are different between A, B, C, and D, and A is according to the embodiment of the present invention. When the secondary winding of the insulating transformer 59 and the bypass capacitors 65 and 66 are provided, B is the insulating transformer 59. When only the secondary winding is used and the bypass capacitors 65 and 66 are removed, C is 2 of the isolation transformer 59.
When the secondary winding is deleted and the bypass capacitors 65 and 66 are provided, D is the case where both the secondary winding of the insulating transformer and the bypass capacitors 65 and 66 are deleted. In addition,
In the case of C and D, since there are no taps i-j, the low frequency common mode choke coil 63 is connected to the taps cd instead. Operation mode I is no fuse breaker 58
Is off, and only a leakage current flows due to a capacitor or the like built in the line filter 56.
B, C, and D show almost the same value. In the operation mode II, the no-fuse breaker 58 is on, the switching power supply, the cooling fan, etc. 62 are on, but the vacuum pump 60 and the diffusion pump 61 are off, and the tap i- on the secondary side of the insulating transformer is j is the case where the voltage is output but the motor 28 is in a stopped state. In the operation mode III, the vacuum pump 60 and the diffusion pump 61 are in the ON state in the operation mode II, and the isolation transformer 59
With or without, there is a bypass capacitor 65, 66
With or without, a lower value indicates a lower value. The operation mode IV is the operation mode III, in which the motor 28 is rotating and accelerating the rotor 27, the switching element 25 is turned on, the bidirectional power converter 22 for the power supply is a boost converter operation, and the bidirectional power converter 26 for the motor is The motor 28 is in a state of performing a powering operation by + / slip v / f control, etc., and a leakage current about twice as large as the connection condition A flows, and 5 to 6 at C and D.
When the motor 28 is in a settling state due to high speed rotation, the operation mode V has a doubled value. In the operation mode VI, the power supply bidirectional power converter 22 is the power regeneration step-down converter operation, and the motor bidirectional power converter. 26 is a motor 28-slip v
The regenerative operation is performed by the / f control or the like, and in any case, the connection condition A has the smallest leakage current as in the operation mode VI. In addition, the leakage current value of the graph in the lower part of Figure 3 is 0.5m
The limit value indicated by A indicates, for example, the value regulated by the Pharmaceutical Affairs Law. In the experiment conducted as described above, only the configuration using the insulating transformer 59 and the bypass capacitors 65 and 66 can comply with the regulation. Has become.

Note that the primary side of the isolation transformer 59 is configured as a partially single-turn transformer capable of tap switching, which is provided for use in areas where the power supply voltage is different, and the no-fuse breaker 58 is provided. Tap the output end C
It is possible to easily cope with this by switching the taps between d and h on the basis of. For example, 100V is applied between taps c and d, and e is 1 based on tap C.
If 20V, f is 220V, g is 230V, and h is 240V, the power supply voltage of the AC power supply 21 is 12 in the illustrated connection.
When it corresponds to 0V and corresponds to the power supply voltage 220V of the AC power supply 21, it is connected to the tap f instead of the tap e as shown by the broken line in the figure. In either case, tap cd
The auxiliary equipment of the centrifuge such as the vacuum pump 60 connected between them and the control device of the motor connected between the insulated secondary taps i-j become 100V, and the tap of the insulating transformer 59 By switching between, it is possible to easily cope with regions with different power supply voltages without changing the rated voltage specifications of the electric devices all together.

Further, in the insulating transformer 59, power is supplied to the auxiliary machinery having less leakage current from the tap of the primary winding single-winding transformer, and is supplied to the insulated secondary winding taps ij. Since they are not connected, the outer dimensions of the insulating transformer 59 can be reduced without increasing the rated capacity of the secondary winding.

[0014]

According to the present invention, the motor for rotationally driving the rotor and the AC power source are connected to the AC power source so that the content of the harmonic components of the current passing through the AC power source is decreased, and one of them is the AC power source. In the power converter which is connected to the other and becomes the output of DC power, and a driver device such as the motor drive inverter connected between the DC output end of the power converter and the motor, the AC Since an isolation transformer is provided between the power supply and the power converter, and a choke coil and a filter circuit consisting of a bypass capacitor between the choke coil and ground are provided between the power converter and the isolation transformer, the power switching element is turned on.・ The leakage current generated by the off operation can be greatly suppressed, and
By the action of this filter circuit, it is possible to prevent noise sent to the AC power supply line.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a control device for a centrifuge motor according to the present invention.

FIG. 2 is a block diagram showing a centrifuge motor control device suitable for applying the present invention.

FIG. 3 is a graph showing a result of measuring a leakage current value corresponding to each operation mode of the present embodiment.

[Explanation of symbols]

21 is an AC power source, 22 is a power converter, 26 is a motor driving driver device, 27 is a rotor, 28 is a motor, 59 is an insulating transformer, 70 is a filter circuit, and 67 is ground.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiro Fujimaki 1060 Takeda, Hitachinaka City, Ibaraki Prefecture, Hitachi Koki Co., Ltd. (72) Inventor Tsutomu Takamura 1060 Takeda, Hitachinaka City, Ibaraki Hitachi Koki Co., Ltd.

Claims (1)

[Claims] 1. A motor that rotationally drives a rotor and an AC power supply are connected to the AC power supply so as to reduce the content of harmonic components of a current passing through the AC power supply. One is connected to the AC power supply and the other is connected. In a centrifuge equipped with a power converter that outputs DC power, and a motor drive driver device connected between the DC output end of the power converter and the motor, the AC power supply and the power An isolation transformer between the converter and
A control device for a centrifuge motor, wherein a filter circuit is provided between the insulation transformer and the power converter.