JP6706756B2 - MOTOR DRIVE DEVICE AND ELECTRIC DEVICE HAVING COMPRESSOR USING THE SAME - Google Patents

Description

The present invention relates to a motor drive device that drives a brushless DC motor by inverter control, and an electric device having a compressor using the motor drive device.

Conventionally, this type of brushless DC motor driving device drives a brushless DC motor based on 120-degree rectangular wave energization of PWM (Pulse-Width-Modulation) control, and energizes when the on-duty of PWM control becomes 100%. By extending the section to 120 degrees or more, the high-speed/high-load drive area is extended (see, for example, Patent Document 1).

FIG. 8 shows a motor drive device described in Patent Document 1. As shown in FIG. 8, when each of the switching elements 3a to 3f forming the inverter 3 shifts from off to on, advance timing control is performed by the on-timing control means 103, and when shifting from on to off, The off-timing control unit 104 does not perform the advance angle control, so that the overlap energization is performed.

Further, the conduction angle, the lead angle, and the inverter input DC voltage are controlled so that the motor drive power reaches the target power value, thereby enabling high output and high rotation while reducing loss (see, for example, Patent Document 2). FIG. 9 shows a motor drive device described in Patent Document 2. As shown in FIG. 9, the brushless DC motor drive control means 201 has power detection means 202 for detecting drive power, and energization pulse signal generation means 203 for generating a drive signal pattern for the inverter and setting an inverter input voltage. , The inverter input voltage value and the conduction angle and advance angle are controlled so that the drive power matches the target set power value.

JP, 2006-50804, A JP, 2008-167525, A

However, in the configuration of Patent Document 1 described above, it is possible to expand the high-load/high-speed drive region by quickly turning on the switching element and extending the power supply section to the brushless DC motor to 120 degrees or more, but the low-load No improvement was seen in the low-speed drive region, and there was a problem that the efficiency of the motor drive device was lower than the circuit and motor loss.

Further, in the configuration described in Patent Document 2, it is necessary to select three independent parameters of the input voltage, the conduction angle, and the advance angle according to each driving state such as the load state and the driving speed state of the brushless DC motor, Increased development man-hours, calculation/selection of 3 parameters according to driving conditions are required, and use of arithmetic elements capable of high-speed calculation accompanying control complexity, or table of optimum values of each parameter according to driving conditions There is a problem that the cost of the motor drive device is increased due to the use of the memory element.

The present invention is to solve the above-mentioned conventional problems, and to reduce the loss of the device when the brushless DC motor is driven at low load and low speed, and to provide a motor drive device of high efficiency and low power consumption at low cost. With the goal.

In order to solve the conventional problems, a motor drive device of the present invention responds to a brushless DC motor, a position detecting unit that detects a rotor position of the brushless DC motor, and a position signal obtained by the position detecting unit. And a voltage supplied to the brushless DC motor at a time ratio of an ON period by switching at a high frequency of the switching element of the inverter, the inverter being configured by six switching elements that are turned on or off. and PWM control means for adjusting said a commutation control section for controlling the timing of on and off switching elements, can in on and off timing of each set independently of the switching element, the PWM control means when the ratio is as 100% of the on period by, by adjusting the Ofuta Lee timing of the switching element, and performs speed control of the brushless DC motor.

As a result, when the brushless DC motor is driven at a low load and at a low speed, it is possible to narrow the section for supplying electric power to the brushless DC motor stator winding, so the number of times the switching element is turned on and off due to PWM control is reduced, The switching loss of the inverter can be suppressed. Further, since the switching element is not turned on and off at high frequencies, switching loss is significantly suppressed, and circuit efficiency can be improved. Further, since the motor current does not generate a high frequency current due to the ON/OFF of the PWM control, the motor efficiency can be improved by reducing the iron loss of the motor, and the efficiency of the motor drive device can be significantly improved. Further, since the high frequency sound is not generated due to the high frequency switching by the PWM control, the motor driving device can be made quiet.

INDUSTRIAL APPLICABILITY The motor drive device of the present invention can achieve high efficiency and low power consumption when the brushless DC motor is driven at low load and low speed.

Block diagram of a motor drive device according to Embodiment 1 of the present invention Waveforms and timing charts of each part in the first embodiment of the present invention Switching elements Ofuta Lee timing adjustment control start determination flowchart Migration flowchart from PWM control to Ofuta Lee timing adjustment control Flowchart illustrating the operation of Ofuta Lee timing adjustment control Diagram showing terminal voltage waveform of brushless DC motor Diagram showing phase current waveform of brushless DC motor Block diagram of conventional motor drive Control block diagram of a conventional motor drive device

A first invention comprises a brushless DC motor, position detecting means for detecting a rotor position of the brushless DC motor, and six switching elements which are turned on or off according to a position signal obtained by the position detecting means. An inverter for supplying electric power to the brushless DC motor; a PWM control means for adjusting a voltage supplied to the brushless DC motor at a duty ratio of an ON period by switching at a high frequency of a switching element of the inverter; A commutation control unit for controlling the timing of turning on and off is provided, and the on and off timings of the switching element can be set independently of each other so that the duty ratio of the on period by the PWM control means becomes 100%. , by adjusting the Ofuta Lee timing of the switching element, it controls the speed of the brushless DC motor. As a result, when the brushless DC motor is driven at a low speed and a low load, the ON period of the switching element can be shortened and the number of times of switching can be reduced, so that the loss of the inverter circuit can be suppressed and the motor drive device can have a high performance. Efficiency can be improved.
Further, since the switching element is not turned on and off at high frequencies, switching loss is significantly suppressed, and circuit efficiency can be improved. Further, since the motor current does not generate a high frequency current due to the ON/OFF of the PWM control, the motor efficiency can be improved by reducing the iron loss of the motor, and the efficiency of the motor drive device can be significantly improved. Further, since the high frequency sound is not generated due to the high frequency switching by the PWM control, the motor driving device can be made quiet.

The second invention is, in the first invention, the switching of the switching element from ON state to the OFF state, fast Thailand timing range with respect to switching from off to on, the electrical angle 0 ° 30 ° It was done in. As a result, the advance angle of the electrical angle 1/2, which accelerates the turn-off of the switching element, is automatically added, and even if the drive waveform has a section in which the power supply to the brushless DC motor is stopped, It is possible to secure stable drive performance that is unlikely to cause tones.

In a third aspect based on the first or second aspect , the commutation control means turns on the switching element at an on timing when the on period duty ratio of the switching element by the PWM control means is equal to or more than a predetermined value. By advancing further, stable startability is secured by using PWM control at the ultra low speed immediately after the start of the brushless DC motor, or at the time of low load/low speed drive, and stable drive at the ultra low load and ultra low speed. The property is improved.

According to a fourth aspect of the present invention, a brushless DC motor driven by the motor drive device according to any one of the first to third aspects drives a compressor of a refrigeration cycle. The COP of the compressor can be improved and a highly efficient refrigeration cycle can be provided.

A fifth invention is an electric device having a compressor driven by the motor drive device according to any one of the first to fourth inventions. As a result, it is possible to provide an electric device with low power consumption by a highly efficient refrigeration cycle, and suppress noise in a high frequency band due to high frequency switching, so that the refrigerator can be quiet.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

(Embodiment 1)
1 is a block diagram of a motor drive device according to a first embodiment of the present invention.

In FIG. 1, the AC power supply 1 is a general commercial power supply, and has an effective value of 100 V 50 Hz or 60 Hz in Japan. The converter circuit 2 converts the AC power supply 1 into a DC voltage. The converter circuit 2 in FIG. 1 is composed of a rectifying circuit 2a in which four diodes are bridge-connected, a smoothing circuit 2b using a capacitor, and a switch section 2c that switches the output voltage, so that the output voltage can be double-voltage rectified or full-wave rectified Although the configuration is switched to the step, a single output configuration of a double voltage rectified output or a full wave rectified output may be used without any problem, and a configuration using a step-up chopper or a step-down chopper or a configuration capable of adjusting the output to an arbitrary voltage may be used.

The inverter 3 is composed of six switching elements 3a to 3f, and MOSFETs are used in this embodiment. Then, each switching element is connected in a three-phase bridge and by switching on/off of an arbitrary switching element, the input DC voltage is converted into a three-phase AC voltage.

The brushless DC motor 4 is composed of a stator having a three-phase winding and a rotor having a permanent magnet, and is driven by the three-phase AC power from the inverter 3.

The position detecting means 5 detects the magnetic pole position of the brushless DC motor. In the first embodiment of the present invention, the phase of the induced voltage generated in the stator winding by the rotation of the rotor (zero cross point ) Is detected, a method using a position sensor such as a Hall IC or a current detecting method using a current sensor may be used.

The speed detecting means 6 detects the drive speed of the brushless DC motor from the output signal of the position detecting means 5. In the present embodiment, the induced voltage zero-cross cycle generated in the stator winding by the rotation of the brushless DC motor rotor is detected. Calculate based on

The error detection means 7 detects the difference between the drive speed of the brushless DC motor 4 obtained by the speed detection means 6 and the target speed.

The commutation control unit 8 sets a phase for supplying electric power to the brushless DC motor stator winding in the range of electrical angle of 90 degrees to 150 degrees based on the signal from the position detection means 5. The commutation control unit 8 and the on-timing control section 9 for setting a Thai when to turn on and off the switching elements 3a to 3f, because it has a OFF timing controller 10, on the switching elements of the inverter 3 It is possible to individually set the timings of turning off and off.

The PWM control means 11 adjusts the output voltage of the three-phase AC output of the inverter by PWM control and controls the brushless DC motor 4 to drive at the target speed. Here, when the PWM on-time duty ratio is larger than the value obtained by dividing the “minimum electrical angle of the power supply section to the brushless DC motor winding” by the “electrical angle of 120 degrees”, the PWM control means has a duty ratio of 100. The off-timing controller 10 accelerates the turn-off timing of the switching element so that the percentage becomes %.

It is desirable to change the turn-off timing gradually in order to prevent a sudden change in the operating state of the brushless DC motor, but there is no particular problem even if it is performed in one control cycle. The speed control of the brushless DC motor 4 by adjusting the ON time ratio by the PWM control means 11 is performed when the driving speed is very low when the brushless DC motor 4 is started, or when the driving load is small. In other states, the PWM control means 11 controls the speed of the brushless DC motor 4 by adjusting the OFF timing of the switching element by the commutation control unit 8 so that the ON time ratio becomes 100%.

The waveform synthesizing unit 12 synthesizes the PWM signal generated by the PWM control unit 11 and the signal generated by the commutation control unit 8, and the drive unit 13 turns on or off the switching elements 3a to 3f of the inverter 3 based on the synthesized signal. In the off state, an arbitrary three-phase AC voltage is generated and supplied to the brushless DC motor 4 to be driven.

The compression element 14 is connected to the shaft of the rotor of the brushless DC motor 4, sucks the refrigerant gas, compresses it, and discharges it. The brushless DC motor 4 and the compression element 14 are housed in the same closed container to form the compressor 15. The discharge gas compressed by the compressor 15 constitutes a refrigeration/air-conditioning system in which the discharge gas passes through the condenser 16, the pressure reducer 17, and the evaporator 18 and returns to the suction of the compressor 15. Since it absorbs heat, it can heat and absorb heat. If necessary, a blower or the like may be used for the condenser 16 and the evaporator 18 to further promote heat exchange. In the first embodiment, the refrigerating and air-conditioning system is used as a refrigerating cycle of the refrigerator 19, and the evaporator 18 is used to cool the food storage chamber 21 surrounded by the heat insulating wall 20.

The operation and action of the motor drive device configured as described above will be described below.

FIG. 2 is a timing chart of the motor drive device according to the first embodiment of the present invention. FIG. 2(1) is a drive waveform and a timing chart at a general 120-degree energization, and (2) is a waveform when a brushless DC motor is driven by adjusting the off timing of the switching element by the off timing control unit 10. And the timing is shown. The induced voltage generated by the rotation of the brushless DC motor 4 is shown as E, the terminal voltage is shown as Vu, and both waveforms show only the U phase, but the V phase and W phase waveforms have the same shape with a phase difference of 120 degrees. It has a waveform. The drive signals of the switching elements 3a, 3b, 3c connected to the high voltage side are shown as U+, V+, W+, and the drive signals of the switching elements 3d, 3e, 3f connected to the low voltage side are 180 times the drive signals of the respective high voltage side SW elements. The waveform becomes out of phase.

The zero cross point of the induced voltage is detected as a position signal in the rotor magnetic pole relative position detection in order to achieve the timing (not shown) for switching the conduction phase of the stator winding. The detection of the zero cross point appears in a section (C1, C2, C3, C4) where no voltage is applied to the phase winding (in the U phase shown in FIG. 2, both switching elements 3a and 3d are turned off). A point (P1, P2) at which the magnitude relationship of the induced voltage and 1/2 of the inverter input voltage Vdc is reversed is detected. Therefore, a position signal is generated every electrical angle of 30 degrees, that is, two times for each phase and six times for a total of three phases per cycle of electrical angle.

Looking at the energization patterns (U+, V+, W+) of the switching elements (high-voltage side connections 3a, 3b, 3c) at 120-degree energization shown in FIG. 2A, after position detection (P1), 30 degrees after electrical angle, W+ By turning on U+ (switching element 3a) at the same time as turning off, the winding of any one of the three phases is always energized in the entire electrical angle range of 360 degrees. On the other hand, in FIG. 2B, after the position detection (P1), W+ (switching element 3c) is turned off before the electrical angle of 30 degrees elapses, and then U+ is turned on after the electrical angle of 30 degrees.

The induced voltage appears in the section C1 to C4 only when the switching element of the other phase is on, that is, only when the PWM is on. Therefore, the switching element is turned off earlier than the turn-on, and the power supply section to the brushless DC motor is shortened. As a result, the power supply section of the fixed winding is shortened, and the number of times of ON/OFF is reduced by PWM control, so that the loss of the inverter circuit can be suppressed. Further, by shortening the power supply section, the ON time of the PWM control becomes longer, and the period in which the position detection signal can be acquired becomes longer, so that the position detection accuracy is improved.

Further, the timing of turning off the switching element is from immediately after the position detection until after the electrical angle of 30 degrees after the position detection (the range of the section A1 with respect to the position detection P1), and the position detection (P1) is reliably detected. The flowable range and the advance phase with respect to the induced voltage are taken into consideration so that the torque decrease due to the delay phase does not occur.

In this way, by setting the off timing of the switching elements (3a to 3f) within 30 degrees immediately after the position detection, the power supply section to the three-phase winding is adjusted to 90 degrees or more and 120 degrees or less, and the power supply is stopped. The shorter the section (A1, A2, A3), the larger the advance angle B (1/2 of the electrical angle of the non-power supply section) is automatically added, the motor torque increases and there is the non-power supply section. Nevertheless, stable driving without step out is possible.

Next, the operation of adjusting the OFF timing of the SW element will be described using a flowchart.

FIG. 3 is a flowchart for determining the start of the off-timing control of the switching element. In FIG. 3, first, in S11, it is confirmed whether the ON time ratio of the switching element generated by the PWM control means 11 is larger than a predetermined value, and if it is larger than the predetermined value, the process proceeds to S12 to start the OFF timing adjustment control. If it is smaller than the predetermined value, PWM control is performed. In the present embodiment, the predetermined value of the on-time ratio is set to 75% from the ratio of 120-degree energization because the minimum power supply section to the winding is 90 degrees in electrical angle, but it is appropriate for the application. Select any value.

Thus when used in combination with PWM control initiation of Ofuta Lee timing adjustment control of the switching element as a time of more than at ratios predetermined PWM on-time, extremely or when the drive speed is low, such as during start, at the time of low speed driving When the load is extremely low, the start-up failure, unstable operating state, or extreme torque drop due to the extremely short power supply section to the winding are prevented, and stable drive is possible under all load conditions. I am trying to make it happen.

FIG. 4 is a flowchart showing the transition from PWM control to off-timing adjustment. When the start of the off-timing adjustment control is determined by the flow shown in FIG. 3, the off-timing of the switching element is advanced by an arbitrary time in S21, and the speed control is performed by PWM control in S22. By increasing the off-timing, the power supply section to the brushless DC motor is shortened, so that the duty ratio of the on-time by the PWM control is increased. When the ON time ratio by PWM control is less than 100 in S23, the process returns to S21 to continue the operation. When the on-time time ratio reaches 100% in S23, the process proceeds to S24, the on-time time ratio is kept at 100%, and the adjustment control of the off timing of the switching element is started in S25.

Next, the speed control of the brushless DC motor after shifting to the off-timing adjustment control of the switching element will be described with reference to FIGS. 1 and 5.

FIG. 5 is an operation flowchart of the off-timing adjustment control of the switching element according to the first embodiment. In FIG. 5, first, in S31, the deviation between the drive speed of the brushless DC motor 4 detected by the speed detection means 6 and the target speed is detected by the error detection means 7, and if it is faster than the target speed, the process proceeds to S32. In S32, the PWM control means 11 holds the on-time duty ratio of 100%, and the off-timing control unit 10 determines whether or not the off-timing can be advanced. Speed control is performed so that the power supply section to the winding is reduced by decreasing the speed of the brushless DC motor (S33), and if impossible, PWM control by the PWM control means 11 is performed (S34). In the first embodiment, the determination as to whether or not the off timing can be advanced can be made by further advancing the off timing when the off timing of the switching element is off immediately after the position detection. Judge that there is no. In the first embodiment, since the lead angle is 0 degree, the minimum power supply section to the stator winding is 90 degree electrical angle.

If the driving speed of the brushless DC motor when it is determined that slower than the target speed (S35), the Ofuta Lee timing of the switching element proceeds to S36 are performed until after the electrical angle of 30 degrees from the detection position, the switching process proceeds to S37 By delaying the off-timing of the element, the speed control is performed so that the drive speed is increased by increasing the power supply period to the brushless DC motor winding. If the off-timing of the off-switching element is at the position where the electrical angle is 30 degrees in S36, the process proceeds to S38. In S38, if the OFF timing of the switching element is further delayed, the applied voltage phase becomes a delayed phase with respect to the induced voltage, and there is a possibility that the motor torque will decrease and step out accompanying this, and therefore the ON timing can be advanced. Speed control is performed such that the power supply section to the winding is increased and the drive speed of the brushless DC motor is increased. The upper limit of advancing the on-timing is until immediately after the position detection, and the maximum power supply section to the winding at this time is an electrical angle of 150 degrees.

Further, since the lead angle in the first embodiment to be 0 degrees, so that Ofuta Lee timing and on-timing of the switching elements is performed to match the energization of an electrical angle of 120 degrees. In the IPM motor in which the permanent magnet is embedded inside the stator, it is necessary to provide an arbitrary advance angle in order to realize optimum driving. Therefore, in order to optimally drive all motors such as the IPM motor, the off-timing adjustment range of the switching element is the position after the position detection and from the position detection timing to "(electrical angle 30 degrees)-(advance angle)". .. The on-timing of the switching element is a timing when “(electrical angle 30 degrees)−(advance angle)” has elapsed from the position detection timing (for example, when the advance angle is 10 degrees, turn-off is from the position detection until the electric angle 20 degrees). The electric angle after position detection is 20 degrees after the position is detected), and the sum of the electric angle from position detection to turn-off and the electric angle from position detection to turn-on is set to 60 degrees or less and turn-off is performed. and the electrical angle of 0 degrees than the turn-on can be adjusted at any value between 30 degrees, and can freely set the Thailand timing of advance and on-off until the electrical angle of 30 degrees from the position detection.

The electric power supply section to the winding when the lead angle is added is adjusted in the electrical angle range of "90 degrees+lead angle" to 120 degrees.

Furthermore, when driving a brushless DC motor 4 at a high speed and high load, Tan'ofuta Lee timing from the position detection - as "(electrical angle 30 degrees) (advance)" elapsed Thailand timing, the turn-on timing immediately after the detection position The power supply section to the winding can be adjusted within the range of 120 electrical angle to 150 electrical angle-advance by adjusting within the range of the timing when only "electrical angle 30 degree-advance" has elapsed from the position detection. ..

Therefore, by adjusting the turn-on and turn-off timings of the switching elements, it is possible to adjust the power supply section to the brushless DC motor in the electrical angle range of 90 to 150 degrees (when the advancing angle is 0 degree), and the low speed and low load can be adjusted. It is possible to drive under a wide range of loads and speeds, from drive to high-speed, high-load drive.

Next, the terminal voltage of the brushless DC motor according to the present embodiment will be described with reference to FIG. 6(1) and (2) show sections C1 and F1 in FIG. 2(1), and FIGS. 6(3) and 6(4) show sections C3 and F2 in FIG. 2(2).

As shown in FIGS. 6(1) and 6(2), FIG. 2(1) showing waveforms in PWM control of 120-degree energization is superimposed with a high frequency PWM carrier frequency component (cycle f). Further, as shown in FIG. 6(1), in the C1 section, a ringing noise component due to the influence of the motor winding, the stray capacitance, etc. is also superimposed at the moment when the PWM is turned on. In the C1 section, the terminal voltage Vu of the brushless DC motor is compared with ½ of the inverter input voltage, and the point at which the magnitude relationship is reversed is detected as the zero-cross point (point P) of the induced voltage of the brushless DC motor. It is erroneously detected as a Px point due to the noise component. This position detection shift causes pulsation and vibration of the drive speed of the brushless DC motor, an increase in noise, a decrease in drive efficiency, and the like.

On the other hand, as shown in FIG. 6C, when the PWM control ON time ratio is 100%, an induced voltage waveform appears in the terminal voltage Vu, and accurate position detection at the zero cross point (point P) is possible. It is possible and stable driving with low noise, low vibration and low loss can be realized.

Further, in the section F1 as shown in FIG. 6(2), switching loss occurs when the switching element is turned on/off at a high frequency by PWM control, but as shown in FIG. 6(4), the on-time ratio 100 %, the switching operation is not performed, so switching loss does not occur, and high efficiency can be realized by reducing circuit loss.

Further, FIG. 7 shows the current flowing through the brushless DC motor. FIG. 7(1) shows a waveform in PWM control with 120-degree energization, and it can be seen that a high-frequency current component accompanying ON/OFF of a switching element in PWM control is superimposed. While this high frequency current component causes the motor iron loss, the high frequency current component does not occur in the operation at the PWM on-time ratio of 100% shown in FIG. 7(2). High efficiency can be achieved.

A refrigerator having a cooling system for driving a compressor with the motor driving device configured as described above will be described.

In recent years, refrigerators have greatly reduced heat intrusion from the outside due to improvements in heat insulation technology such as the use of vacuum heat insulating materials. For this reason, except during housework hours in the morning and evening when doors are frequently opened and closed, the refrigerator interior is in a stable cooling state for most of the day, and the compressor can be driven at low speed and low load with reduced refrigeration capacity. Has been done. Therefore, in order to reduce the power consumption of the refrigerator, it is very effective to increase the driving efficiency of the compressor, that is, the brushless DC motor at low speed and low output.

In the first embodiment of the present invention, in a state in which the brushless DC motor is driven at a low speed and a low load, the high frequency on/off control by the PWM control is not performed, and the PWM on time ratio is set to 100% and the brushless DC motor is set. The drive speed is controlled while adjusting the power supply section to the winding. As a result, since the inverter 3 does not generate switching loss due to PWM control, it is possible to significantly improve the efficiency of the inverter circuit.

In this embodiment, a MOSFET is used as the switching element of the inverter 3. Due to its structural characteristics, the MOSFET does not have a PN junction in the path of the output current at the time of on, so that the loss at the time of on at the time of low current output is extremely low compared with other power devices such as IGBT. ..

As mentioned above, the refrigerator is driven at low speed and low load for most of the day, so the current flowing through the brushless DC motor is low. Therefore, when the present invention is used to drive a compressor of a refrigerator, using MOSFET as a switching element of the inverter 3 is very effective in reducing power consumption of the refrigerator.

Further, since the ON/OFF control by the PWM control is not performed, there is no high frequency current component in the winding current of the brushless DC motor, the motor iron loss can be significantly suppressed, and the motor efficiency can be improved.

Further, in PWM control, switching operation is generally performed at a PWM frequency of about 1 kHz to 20 kHz, and this frequency component is generated as noise. Since the refrigerator is operated all day regardless of day or night, the silent design is very important. The motor drive device of the first embodiment has a duty ratio of 100% for the on-time, which is caused by the PWM control. It is very effective for quiet design of refrigerators because it eliminates the generation of noise.

As described above, in the first embodiment, the brushless DC motor 4, the inverter 3 that supplies electric power to the brushless DC motor 4, and the position detection unit 5 that detects the rotor position of the brushless DC motor 4 are provided. is composed of six switching elements to be turned on or off in response to the position signal obtained by the position detection means 5, a Thailand when to turn off the switching elements of the inverter 3 to the position signal of the position detecting means 5 By advancing from the timing of turning on, the period of fixing the brushless DC motor and supplying power to the winding can be shortened, so the on-time ratio by PWM control becomes large, and the high-frequency current component of the brushless DC motor is increased. As a result, the iron loss of the brushless DC motor can be reduced. Further, the number of times the switching element is turned on and off due to the PWM control is reduced, and the efficiency of the motor drive device can be improved by reducing the inverter loss.

Further, in this embodiment, by switching the switching elements of the inverter 3 in the high frequency, the PWM control means 11 for adjusting the voltage supplied to the brushless DC motor 4, to control the Thai timing for turning on and off the switching element a commutation control section 8, as the time ratio of the on time by the PWM control unit 11 is 100%, the adjusting Ofuta Lee timing of the switching element, greatly switching losses associated with turning on and off the switching element Therefore, the efficiency of the inverter 3 can be improved. Further, since a high frequency component is not generated in the current flowing through the brushless DC motor due to the high frequency on/off of the switching element, the motor iron loss can be significantly suppressed. As a result, it is possible to provide a highly efficient motor drive device with reduced loss of the brushless DC motor and the circuit. Further, since the on-time ratio of the PWM control is 100%, noise in the high frequency band due to high frequency switching is not generated, and the device can be made quiet. Further, the driving with the on-time ratio of 100% can eliminate the position detection deviation due to the influence of ringing noise and realize the accurate position detection, so that the driving stability can be further improved, whereby the motor driving device can be further improved. Efficiency, low noise, and low vibration can be achieved.

Further, switching of the switching element from the on state to the off state, to the switching from the OFF state to the ON state, by performing an early Thailand timing in the range of electrical angles of 0 ° to 30 °, earlier than the turn-on turn-off Since a lead angle of 1/2 of the electrical angle is automatically added, stable driving is possible without occurrence of step-out or the like even when driving with a driving waveform having a power supply suspension period. Become.

As for the switching timing of the energized phase of the brushless DC motor stator winding, the sum of the electrical angle for advancing the off timing of the switching element and the electrical angle for advancing the on timing of the position signal of the position detection means is the electrical angle 60. The electrical angle for advancing the off-timing is equal to or less than the electrical angle for advancing the on-timing. As a result, the advance angle and the power supply suspension period to the brushless DC motor can be set in the electrical angle range of 0 degree to 30 degrees, so that the optimum power supply period can be set depending on the load and the driving speed state of the brushless DC motor. Since it becomes possible to optimally drive an embedded magnet (IPM) motor that needs to give an optimum advance angle depending on the load state and speed, various types of permanent magnet motors can be driven with high efficiency.

Further, a power supply section to the three-phase winding of the brushless DC motor is set to an electrical angle of 90 degrees or more and 150 degrees or less, and when the power supply section is 90 degrees or more and less than 120 degrees, the switching element is turned off. in the manner to advance from Lee timing, it is possible to realize the optimal driving conditions in a wide range of load and driving speed range of the brushless DC motor.

Further, when the ON time ratio of the switching element by the PWM control means 11 is equal to or more than the predetermined value, the commutation control unit 8 advances the OFF of the switching element from the ON timing, so that the PWM ON time ratio becomes lower than the predetermined value. Even when starting up, or when the load is extremely low during low-speed driving, the start-up failure due to the extremely short power supply section to the winding, unstable operation during driving, or extreme torque drop, etc. This is to prevent it and to realize stable drive under all load conditions.

In addition, the brushless DC motor drives the compressor of the refrigeration cycle, thereby improving the motor efficiency by reducing the iron loss, thereby providing the compressor having a high COP and the refrigeration cycle having the high efficiency.

Furthermore, if a refrigeration cycle that drives a compressor with the motor drive device of the present invention is adopted in a refrigerator, the circuit efficiency of the motor drive device is improved and the high-efficiency refrigeration cycle using a high COP compressor is adopted, thereby reducing the power consumption. A low refrigerator can be provided, and noise in the high frequency band is not generated due to the switching operation of the PWM control, so that the refrigerator can be quiet.

As described above, since the motor drive device according to the present invention can reduce the circuit loss of the motor drive device, improve the motor efficiency, and reduce the drive noise and vibration, the refrigerator, the air conditioner, the washing machine, the pump, the fan, It can be applied to any device using a brushless DC motor, such as a fan and an electric vacuum cleaner.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Converter circuit 3 Inverter 4 Brushless DC motor 5 Position detection means 6 Speed detection means 7 Error detection means 8 Commutation control part 9 On-timing control part 10 Off-timing control part 11 PWM control means 12 Waveform synthesis part 13 Drive means 14 Compressing Element 15 Compressor 16 Condenser 17 Decompressor 18 Evaporator 19 Refrigerator 20 Insulation Wall 21 Food Storage Room

Claims (5)

Brushless DC motor,
Position detecting means for detecting the rotor position of the brushless DC motor,
An inverter configured by six switching elements that are turned on or off according to the position signal obtained by the position detection means, and that supplies electric power to the brushless DC motor;
PWM control means for adjusting the voltage supplied to the brushless DC motor at a duty ratio of an ON period by switching at a high frequency of a switching element of the inverter,
A commutation controller that controls the timing of turning on and off the switching element ,
The on and off timings of the switching element can be set independently of each other,
Wherein as the time ratio of the on period by the PWM control unit is 100% by adjusting the Ofuta Lee timing of the switching element,
A motor drive device for performing speed control of the brushless DC motor. Switching from the on state to the off state the switching element, to the switching from the OFF state to the ON state, the motor driving apparatus according to claim 1 carried out at an early Thailand timing in the range of electrical angles of 0 ° to 30 ° .. The motor drive device according to claim 1 or 2 , wherein the commutation control unit advances the turning-off of the switching element from the on-timing when the duty ratio of the ON period of the switching element by the PWM control unit becomes equal to or more than a predetermined value. The brushless DC motor, the motor driving apparatus according to any one of claims 1 to 3, characterized in that to drive the compressor of the refrigeration cycle. Electrical equipment having a compressor driven by the motor driving device according to any one of claims 1 to 4.

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