JP2003219687A - Motor drive unit, blower, compressor, and refrigerating air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inexpensive and small-sized motor drive unit which is high in conversion efficiency and produces low noise and electromagnetic noise, a blower and a compressor using the motor drive unit, and a refrigerating air conditioner using these items. <P>SOLUTION: The motor drive unit uses an inverter circuit wherein a plurality of upper and lower arms with a switch element connected in series are connected in parallel to a direct-current power source, and alternating-current power is outputted from the series junction points of the switch elements. A PNP junction transistor is used for the upper switch element, and the emitter of the junction transistor is connected with the positive pole side of the direct- current power source. The anode of SiC-SBD is connected with the collector of the junction transistor, and the cathode of the SiC-SBD is connected with the emitter of the junction transistor. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive unit for a DC brushless motor driven by a high-voltage DC power supply, a blower and a compressor using the same, and a refrigerating and air-conditioning apparatus using the blower and the compressor. is there.

[0002]

2. Description of the Related Art FIG.
It is a circuit diagram for one phase in the conventional low-loss, low-noise power conversion circuit shown in Japanese Patent Publication No. In the figure, 10
Reference numeral 1 is a DC power supply, 102 is a positive electrode of the DC power supply 101, 103 is a negative electrode of the DC power supply 101, 104 is a load connected to a conversion circuit, and 105 and 106 are insulated gate bipolar transistors (IG) that perform a switch operation.
It is a switch using BT). Reference numerals 107 and 108 denote free wheel diodes (FRD) that prevent the terminal voltage of the load 104 from jumping up when the switches 105 and 106 are off, and silicon carbide (SiC) diodes are used.

Next, the operation will be described. Switch 1 in Figure 7
By using 05 and 106, one end of the load 104 can be made a positive and negative voltage of the DC voltage. Switch 105,
By changing the opening / closing time of 106, the voltage applied to the load 104 is changed to generate an AC voltage and drive the load 104. The application of the AC voltage to the load 104 is usually realized by performing pulse width modulation (PWM) in which the switches 105 and 106 are turned on / off once within a fixed carrier cycle.

If the load 104 is an inductive load, the load 10
Switch 105, 1 at the timing when current is flowing through 4
When both 06 are turned off, the diodes 107, 1
When 08 is turned on and the current continues to flow in the load 104, the terminal voltage of the load 104 jumps up so that the terminal voltage becomes equal to or higher than the power supply voltage, and an overvoltage is applied to the switch element so that the switch element is not destroyed.

However, when the switches 105 and 106 are turned off, and the current is flowing through the diodes 107 and 108, and when the switches 105 and 106 are turned on again, the diodes 107 and 108 are suddenly reverse-biased from the forward bias. Behavior occurs. In this conventional power conversion circuit, since silicon carbide diodes are used for the diodes 107 and 108, the diode 107,
The recovery current generated by the elimination of the charge accumulated in 108 can be made smaller than that of the silicon FRD. Therefore, the recovery current flowing through the switch element during the ON operation of the switch element is small and the loss can be reduced, so that the power conversion circuit with low loss can be obtained. Also, the electromagnetic noise due to the recovery current, which has a very large current change per unit time, is smaller than that when the silicon FRD is used.

[0006]

The conventional power conversion circuit is configured as described above and uses silicon carbide FRD, which is much more expensive than silicon FRD, in both upper and lower stages. Although higher speed and lower switch loss, an IGBT which is more expensive than a junction transistor is used for both upper and lower stages. Since the upper IGBT is a voltage-driven element and has a high potential with respect to the emitter of the lower IGBT, it is necessary to provide separate upper and lower power supplies for driving, and a power supply circuit for driving is required. The provision of the power supply circuit increases the circuit space and cost. Therefore, although the loss is low and the noise is low, the cost of the entire circuit is extremely high, and the low-capacity inverter circuit that requires low cost and the motor are more expensive than the induction motor, and the cost of the drive circuit can be reduced accordingly. There is a problem that it is not suitable for the required drive circuit of DCBLM (DC brushless motor). A separate power supply is required to drive the upper and lower switches, so a mounting area is required.
There is also a problem that the power conversion circuit becomes large.

The present invention has been made to solve the above-mentioned problems, and provides a motor drive device which is inexpensive, has high conversion efficiency, is small in size, has low noise, and has a small electromagnetic noise, and a motor drive device thereof. An object is to obtain a blower and a compressor that are used and a refrigerating and air-conditioning apparatus that uses them.

[0008]

In a motor drive device according to the present invention, a plurality of upper and lower arms in which switching elements are connected in series are connected in parallel to a DC power source, and AC power is supplied from a series connection point of the switching elements. In a motor driving device using an inverter circuit for outputting, PN is used for the upper switch element.
A P-type junction transistor was used, the emitter of the junction transistor was connected to the positive side of the DC power supply, the collector of the junction transistor was connected to the anode of SiC-SBD, and the emitter of the junction transistor was connected to the cathode of SiC-SBD. Is characterized by.

Further, the motor drive device according to the present invention is
It is characterized in that only the lower switch element is driven by pulse width modulation.

Further, the motor drive device according to the present invention is
A MOSFET is used for the lower switch element.

The motor drive device according to the present invention is
An IGBT is used for the lower switch element, and a silicon diode is used for the lower flyhole diode.

The motor drive device according to the present invention is
The PWM carrier frequency is inaudible.

The motor drive device according to the present invention is
It is characterized in that the switching element of the main circuit is driven by one low-voltage DC power supply.

Further, the motor drive device according to the present invention is
It is characterized by driving a synchronous motor.

The blower according to the present invention is defined by claims 1 to 7.
A motor is driven by the motor drive device described in any one of 1.

The compressor according to the present invention is characterized by any one of claims 1 to 7.
A motor is driven by the motor drive device described in any one of 1.

A refrigerating and air-conditioning apparatus according to the present invention is the eighth aspect.
The blower according to claim 9 or the compressor according to claim 9 is used.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 to 5 are views showing a first embodiment, FIG. 1 is a circuit diagram of one phase of a main circuit of a motor drive device, FIG. 2 is a diagram showing a load circuit and an overall configuration of the motor drive device, and FIG. Junction transistor and MOSFE of motor drive device
FIG. 4 is a timing diagram showing the switch operation of T and the blower motor phase voltage, FIG. 4 is a diagram showing the structure of the outdoor unit of the air conditioner using the blower and its drive device, and FIG. 5 is the details of the control means and one phase of the main circuit. It is a circuit diagram showing.

In FIG. 1, 4 is a DC power supply, 5 is an inductive load such as a synchronous motor, 21 is a junction transistor using silicon as an upper switching element, and 11 is connected between the base and emitter of the junction transistor 21. Resistance, 22
Is a MOSFET using silicon which is the lower switch element
T and 33 are silicon carbide Schottky barrier diodes (SiC-SBD) using silicon carbide.

In FIG. 1, the positive electrode of the DC power supply 4 is connected to the emitter of the junction transistor 21 and the cathode side of the SiC-SBD 33. The collector of the junction transistor 21 and the anode of the SiC-SBD 33 are connected to the inductive load 5 and the drain of the MOSFET 22. M
The OSFET 22 has a parasitic diode in parallel in the same silicon chip. The source of the MOSFET 22 is connected to the negative side of the DC power supply 4.

FIG. 2 is a diagram showing a load circuit and an overall configuration of the motor drive device. As an inductive load, a synchronous motor for driving a blower of an air conditioner using a refrigerant circuit is connected. In FIG. 2, 21 to 26 are switches of an inverter for switching a DC voltage to generate an AC voltage, 21, 23 and 25 are junction transistors using silicon, and 22, 24 and 26 are MOSFETs.

36 to 38 are junction transistors 21 and 2
A resistor connected between the base and emitter of 3, 25.
33 to 35 are currents flowing from the load to the DC power supply side, and when the MOSFETs 22, 24 and 26 are turned off,
This is a SiC-SBD that is forward-biased and allows regeneration and reflux current of a blower synchronous motor 27 to be described later to flow.

30 to 32 are junction transistors 21 and 2
It is a diode that is reverse-biased when 3, 25 are turned off, forward-biased between the collector and base, and blocks a current passing through the resistors 36 to 38 between the collector and the base and between the base and the base-emitter.

Reference numeral 29 is a junction transistor 21, 23, 25.
And when switching MOSFETs 22, 24 and 26,
It is a snubber capacitor that absorbs sharp voltage fluctuations between the DC bus PN due to the inductance between the DC power supply and the load.

Reference numeral 27 denotes a three-phase synchronous motor which rotates in synchronization with the AC voltage generated in the main circuit of the voltage type inverter composed of the above-mentioned electronic parts during normal operation, and is usually DCBL.
M is a blower synchronous motor in which M is used. A fan is mechanically connected to the blower synchronous motor 27 to form a blower that radiates heat in the refrigeration cycle.

Numeral 28 detects the phase voltage of the motor during steady operation of the blower synchronous motor 27, and the junction transistors 21, 2
It is a motor control means for turning on / off the MOSFETs 3, 25 and the MOSFETs 22, 24, 26 and rotating the DCBLM.

FIG. 3 is a timing diagram showing the switch operation of the junction transistors and MOSFETs of the motor drive and the blower motor phase voltage. Details will be described later, but FIG.
A to L are junction transistors 21, 23, 25 during one electrical rotation cycle of the DCBLM of the blower synchronous motor 27.
And the respective conduction sections between the timings at which the MOSFETs 22, 24 and 26 switch conduction.

FIG. 4 shows the structure of the outdoor unit of the air conditioner using the blower and its drive device. FIG. 4 (a) is a front view of the outdoor unit, and FIG. 4 (b) is a top view of the outdoor unit. , Fig. 4
(C) is a side view of an outdoor unit. In the figure, 54 is a compressor for compressing a refrigerant, 55 is a blower, 56 is a heat exchanger,
57 is a circuit including a power supply device and an inverter device.

Circuit 5 including power supply device and inverter device
In 7, the compressor 54 and the blower 55 are driven to operate as an air conditioner using a refrigerant.

A heat exchanger 56 is arranged in the air path of the blower 55 to perform heat exchange. The blower drive circuit described above is also mounted on the circuit 57 including the power supply device and the inverter device. A circuit 5 including a power supply device and an inverter device
A heat dissipation fin of the switch element and a choke coil, which is a noise countermeasure component, are also mounted on the switch 7 as a countermeasure against electromagnetic noise on the power line.

FIG. 5 is a circuit diagram showing details of the control means and one phase of the main circuit. In FIG. 5, reference numerals 4, 5, 11,
21, 22, 30, 33 show the same parts as in FIG. Reference numeral 6 is a base resistance that is connected to the base of the junction transistor 21 and flows a bias current. 7 is a junction transistor 21
In the NPN transistor using silicon for controlling the base current of, the collector is connected to the base resistor 6 and the emitter is connected to the negative side of the high voltage DC power supply 4.

Reference numeral 8 is a base resistor which is connected to the base of the NPN transistor 7 and flows a bias current. Reference numeral 9 is a one-chip silicon control IC that operates with a low voltage power supply and is manufactured by a low voltage silicon process. Reference numeral 10 designates 5 for driving the control IC 9, the NPN transistor 7 and the MOSFET 22.
It is a low voltage DC source of V.

Next, the operation of this embodiment will be described. First, the operation on / off state of each switch in FIG. 2 will be described with reference to FIG. In the energization section of A of FIG. 3,
The junction transistor 25 is always on and the MOSFET 24
Performs PWM. By this switch operation, a voltage is applied from the W phase to the V phase of the blower synchronous motor 27 in the A energization section. MOSFET 24 on the lower side of the V phase in the energization section A
In PWM, the MOSFET 24 has a constant carrier cycle of 50 μs at which the switch frequency becomes an inaudible frequency of 20 kHz.
The on / off is repeated once within ec, and the applied voltage is controlled by the ratio of the on time and the off time.

The on / off operation of the MOSFET 24 will be examined in detail. When the MOSFET 24 is on, the positive electrode of the DC power supply 4, the junction transistor 25, the diode 32, the W phase and the V phase of the blower synchronous motor 27 are switched to the MOSFET 24.
And flows to the negative electrode side of the DC power supply 4.

Thereafter, when the MOSFET 24 is turned off, the diode 34 is forward-biased and turned on, and the current passes through the diode 34 and the junction transistor 25 and the diode 32.
And is recirculated in the motor and maintained. Further, at that time, the diode 31 is reverse-biased, so that the current passing through the collector, the base and the resistor 37 of the junction transistor 23 is not generated, and the charge is not accumulated in the junction transistor 23.

Then, when the MOSFET 24 is turned on again, the electric charge accumulated in the diode 34 during the forward bias and the motor current which continues to flow flow through the MOSFET 24.

Further, since there is the diode 31, MOSFE
As described above while T24 is off, since no charge is accumulated in the junction transistor 23, the junction transistor 23 is not turned on by the accumulated charge when the MOSFET 24 is turned on. Therefore, the junction transistor is used in the upper stage. However, the upper and lower short-circuit operation due to the charge accumulated in the junction transistor does not occur.

In the energizing section A, all the junction transistors and MOSFETs other than those described above are off, the U phase of the blower synchronous motor 27 is de-energized, and an induced voltage corresponding to the position of the rotor appears in the U phase. . Since the induced voltage of this phase is generated in synchronization with the position of the rotor, the timing of transition from the induced voltage to the next energization section B is determined and the synchronous operation is performed.

In the energization section B, the junction transistor 25 is turned off and the junction transistor 21 is turned on in the energization section A. As a result, the voltage applied from the W phase to the V phase is
Switching from U-phase to V-phase application Synchronous motor for blower 2
The magnetic field generated in 7 is rotated. At this time MOSFET 2
4 controls the voltage applied between the lines by performing PWM as in the section A. In the energized section B, the W phase of the blower synchronous motor 27 is in the non-energized state, and the induced voltage corresponding to the position of the rotor appears in the W phase. Based on the information of the induced voltage of this phase, the timing for shifting to the next energization section C is determined in synchronization with the position of the rotor.

In the energized section C, the MOSF is compared with the energized section B.
The ET 24 is turned off and the MOSFET 26 is PWMed.
As a result, the voltage applied from the U phase to the V phase is switched to the application from the U phase to the W phase, and the magnetic field generated in the blower synchronous motor 27 is rotated.

By repeating the same operation, the applied voltage is switched in synchronization with the motor to generate a rotating magnetic field to operate the motor.

Next, the drive circuit of the MOSFET and the junction transistor and the operation thereof will be described with reference to FIG. The source of the lower MOSFET 22 has the same potential as the ground potential of the control IC 9, and since the voltage is driven, the control I of 5 V operation is used.
Drive directly using C9.

Since the junction transistor 21 is a PNP transistor, it is turned on / off by driving the base with the high breakdown voltage NPN transistor 7. NPN at this time
The emitter of the transistor 7 has the same potential as the reference potential of the control IC 9, and is directly base-driven by the control IC 9. Thus, the single low voltage DC power supply 10 can drive the junction transistor and MOSFET of the main element.

Since the motor is driven by such an operation,
The upper junction transistors switch only once during one electric cycle of the motor, and switch loss hardly occurs. The electric cycle of the motor is at most several tens to several hundreds Hz in the air conditioner blower. Also, the lower MOSFET performs PWM operation at an inaudible frequency of 20 kHz, so that it frequently turns on and off, but the upper FRD is a silicon carbide Schottky diode that has significantly less accumulated charge than a silicon diode, so the MOSFET caused by the accumulated charge The on loss of is extremely small, and the motor can be driven with almost no loss. Further, almost no electromagnetic noise is generated when the accumulated charges steeply flow into the MOSFET.

In the main circuit configuration, the upper transistor is an inexpensive junction transistor, and the lower side is originally a MOSFET having parasitic FRD, so that only one silicon carbide FRD having high performance but expensive is provided per phase. Since the low-loss and low-noise drive as described above can be realized without using it, a remarkably low-cost motor drive device can be obtained.

Further, since the switching element of the main circuit can be driven by a single power source of the low voltage DC power source 10, the driving device can be realized at low cost and space saving.

The above effects are very suitable for a drive unit of a DC BLM for a blower for an air conditioner, which is originally required to have low loss and low noise, and has a small power capacity, which is required to be low in cost and downsized.

Further, it is particularly suitable for a drive device of a drive circuit built-in type DCBLM in which the drive circuit is installed in a limited space in the motor.

Embodiment 2. FIG. 6 shows the second embodiment and is a circuit diagram of one phase of the main circuit of the DCBLM drive device. In the figure, 21 is a junction transistor using silicon which is an upper switching element, 11 is a resistor connected between the base and emitter of the junction transistor 21, 60 is a silicon insulated gate bipolar transistor (IGBT) which is a lower switching element, 61 is a diode using silicon, 33 is a SiC-SBD using silicon carbide,
Reference numeral 4 is a DC power source, and 5 is a synchronous motor of an inductive load such as a synchronous motor.

In FIG. 6, the positive electrode of the DC power supply 4 is connected to the emitter of the junction transistor 21 and the cathode side of the SiC-SBD 33. The collector of the junction transistor 21 and the anode of the SiC-SBD 33 are connected to the inductive load 5 and the drain of the IGBT 60. The IGBT 60 and the diode 61 are connected in parallel. Also IGBT60
The emitter of is connected to the negative side of the DC power supply 4.

In the present embodiment, the lower switching element and FRD of the above-mentioned Embodiment 1 are silicon diodes which are separate chips from the IGBT, but the number of chips is increased by one, but the same effect as in Embodiment 1 is obtained. can get.

The control means of FIG. 5 shown in the first embodiment can be applied to this embodiment.

Embodiment 3. In the first embodiment, the three-phase synchronous motor has been described as an example.
The same effect can be obtained by using a motor having more than two phases. Moreover, the effect is higher when a motor having a larger number of phases is used.

In the above embodiment, the synchronous motor is used as an example of the motor, but the motor is not limited to the synchronous motor. It may be an induction motor.

In the above embodiment, only the lower switch element is PWM driven, but the upper and lower switch elements may be PWM driven. Even in this case, driving with low loss and low noise can be realized.

By mounting the motor drive device of the present invention on a blower, a high efficiency, small size, low electromagnetic noise motor drive device and a high efficiency motor are combined to obtain a high efficiency motor.
A blower that is small, inexpensive, and has low electromagnetic noise can be obtained.

By mounting the motor drive device of the present invention on a compressor, a highly efficient and compact motor drive device with a small electromagnetic noise and a highly efficient motor are combined.
A compressor with high efficiency, small size, low cost, and low electromagnetic noise can be obtained.

By using the blower or compressor equipped with the motor drive device of the present invention in a refrigeration / air-conditioning system, a refrigeration / air-conditioning system with high efficiency, small size, low cost, and low electromagnetic noise can be obtained.

[0059]

In the motor drive device according to the present invention, a PNP junction transistor is used as the upper switching element, the emitter of the junction transistor is connected to the positive side of the DC power source, and the collector of the junction transistor is the anode of the SiC-SBD. Connected to the emitter of the junction transistor with SiC
-By connecting the cathode of SBD, high efficiency,
It is possible to obtain a small-sized, inexpensive motor drive device with low electromagnetic noise.

Further, the motor drive device according to the present invention is
By pulse-width-modulating only the lower switch element, it is possible to obtain a motor drive device with extremely high efficiency, small size, low cost, and low electromagnetic noise.

The motor drive device according to the present invention is
By using MOSFET for the lower switch element,
It is possible to obtain a motor drive device having high efficiency, small size, low cost, and low electromagnetic noise.

Further, the motor drive device according to the present invention is
By using the IGBT as the lower switch element and the silicon diode as the lower flyhole diode, it is possible to obtain a motor drive device with high efficiency, small size, low cost, and low electromagnetic noise.

Further, the motor drive device according to the present invention is
By setting the PWM carrier frequency to an inaudible frequency, noise reduction of the motor drive device can be achieved.

The motor drive device according to the present invention is
By driving the switching element of the main circuit with one low-voltage DC power supply, the cost and space of the motor drive device can be reduced.

Further, the motor drive device according to the present invention is
By driving the synchronous motor, it is possible to further improve the efficiency by combining with the synchronous motor with low loss.

The blower according to the present invention is defined by claims 1 to 7.
By driving the motor by the motor drive device described in any one of 1, a blower with high efficiency, small size, and low electromagnetic noise can be obtained.

The compressor according to the present invention is characterized by any one of claims 1 to 7.
When the motor is driven by the motor drive device described in any one of 1, the compressor with high efficiency, small size, low cost, and small electromagnetic noise can be obtained.

The refrigerating and air-conditioning apparatus according to the present invention is the eighth aspect.
By using the blower according to claim 9 or the compressor according to claim 9, it is possible to obtain a refrigerating and air-conditioning apparatus with high efficiency, small size, low cost, and low electromagnetic noise.

[Brief description of drawings]

FIG. 1 shows the first embodiment and is a circuit diagram of one phase of a main circuit of a motor drive device.

FIG. 2 is a diagram showing the first embodiment and is a diagram showing a load circuit and an overall configuration of a motor drive device.

FIG. 3 is a diagram showing the first embodiment and is a timing diagram showing a switch operation of a transistor and a MOSFET of a motor drive device and a blower motor phase voltage.

FIG. 4 is a diagram illustrating the first embodiment and is a diagram illustrating a structure of an outdoor unit of an air conditioner that uses a blower and a drive device thereof.

FIG. 5 is a diagram showing the first embodiment and is a circuit diagram showing details of a control unit and one phase of a main circuit.

FIG. 6 shows the second embodiment and is a circuit diagram of one phase of a main circuit of the motor drive device.

FIG. 7 is a circuit diagram of one phase of a conventional power conversion circuit.

[Explanation of symbols]

4 DC power supply, 5 inductive load, 6 base resistance, 7
NPN junction transistor, 8 resistance, 9 control IC, 1
0 low voltage DC power supply, 11 resistance, 21,23,25 junction transistor, 22,24,26 MOSFET, 2
7 blower synchronous motor, 28 control means, 29 condenser, 30, 31, 32 diode, 30 diode, 33, 34, 35 SiC-SBD, SiC diode, 54 compressor, 55 blower, 56 heat exchanger, 57 power supply device And a circuit including an inverter device, 6
0 IGBT, 61 FRD.

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Claims (10)

[Claims] 1. A motor drive device using an inverter circuit in which a plurality of upper and lower arms in which switch elements are connected in series are connected in parallel to a DC power source, and AC power is output from a series connection point of the switch elements. A PNP junction transistor is used as the upper switch element, the emitter of the junction transistor is connected to the positive side of the DC power supply, and the collector of the junction transistor is a Schottky barrier diode made of silicon carbide as a raw material (hereinafter referred to as SiC-SBD). ) Is connected, and the cathode of the SiC-SBD is connected to the emitter of the junction transistor. 2. The motor drive device according to claim 1, wherein only the lower switch element is driven by pulse width modulation (PWM). 3. A MOSFET (meta
3. The motor drive device according to claim 1, wherein an oxide semiconductor field effect transistor) is used. 4. An IGBT (insulate) is attached to the lower switch element.
3. The motor drive device according to claim 1, wherein a d-gate bipolar transistor) is used, and a silicon diode is used for the lower flyhole diode. 5. The motor drive device according to claim 1, wherein the PWM carrier frequency is an inaudible frequency. 6. The motor drive device according to claim 1, wherein the switching element of the main circuit is driven by one low-voltage DC power supply. 7. The motor drive device according to claim 1, which drives a synchronous motor. 8. A blower in which a motor is driven by the motor drive device according to any one of claims 1 to 7. 9. A compressor characterized in that a motor is driven by the motor drive device according to any one of claims 1 to 7. 10. A refrigerating and air-conditioning apparatus using the blower according to claim 8 or the compressor according to claim 9.