JP2015080314A - Power conversion device and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a possibility that an element of a power factor improvement unit breaks down while suppressing a pressure resistance of the element.SOLUTION: A power conversion device comprises: a rectification unit (22) which rectifies input AC; a power factor improvement unit (25) which performs power factor improvement operation for an input voltage (V1) output from the rectification unit (22); a power conversion unit (28) which is connected to an output of the power factor improvement unit (25) and generates output AC power; and a control unit (31) which controls the power factor improvement unit (25). When stopping the operation of the device driven by the power conversion unit (28), the control unit (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation and then instructs the power conversion unit (28) to stop the operation.

Description

  The present invention relates to a power converter and an air conditioner having a power factor improving unit, and more particularly to control when stopping the operation of a device driven by the power converter.

  Generally, a compressor in an air conditioner uses a motor as a drive source. AC power is supplied to the motor from the power converter.

  As a power conversion device, as disclosed in Patent Document 1, a device mainly composed of a rectification unit, a step-up power factor correction unit, and an inverter type power conversion unit is generally known. First, the AC commercial voltage output from the commercial power source is rectified by the rectification unit. The rectified voltage is boosted to a desired voltage by the power factor improving unit and smoothed, whereby the power factor is improved. The voltage after the power factor improvement is supplied to the power conversion unit. The power conversion unit generates AC power for driving the motor using the voltage after the power factor is improved.

JP 2011-239547 A

  The power factor improving unit performs a switching operation so that the output voltage is maintained at a set value. However, when the power conversion unit stops, the load decreases rapidly, so that the control of the power factor improvement unit cannot follow, and the output voltage of the power factor improvement unit may suddenly increase. Then, a higher voltage than usual is applied to the switching element of the power factor correction unit and the smoothing capacitor.

  If a switching element or a smoothing capacitor that can withstand overvoltage is used, failure due to overvoltage can be avoided. However, if it does so, an element will enlarge and cost will also rise.

  An object of the present invention is to suppress the possibility of failure of these elements while suppressing the pressure resistance of the elements of the power factor improvement unit.

  A power conversion device according to a first aspect of the present invention includes a rectifying unit (22) for rectifying an input AC from an AC power source (91), and a power factor improvement for an input voltage (V1) output from the rectifying unit (22). A power factor improvement unit (25) that performs an operation, a power conversion unit (28) that is connected to an output of the power factor improvement unit (25) and generates output AC power, and a power factor improvement unit (25) And a control unit (31) for controlling the power factor correction operation. When stopping the operation of the device driven by the power conversion unit (28), the control unit (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation, and then The conversion unit (28) is instructed to stop the operation.

  According to this, since the power factor improvement unit (25) is instructed to stop the power factor improvement operation and then the power conversion unit (28) is instructed to stop the operation, the output of the power factor improvement unit (25) An increase in voltage can be suppressed. The voltage applied to the switching elements of the power factor improving unit and the smoothing capacitor can be suppressed, and the possibility of failure of these elements can be suppressed while suppressing the withstand voltage of these elements.

  In the power converter of the second invention, in the first invention, the controller (31) instructs the power factor improving unit (25) to stop the power factor improving operation after a predetermined time has elapsed. Instructs the power converter (28) to stop the operation.

  According to this, since a power factor improvement unit (25) is instructed to stop the power factor improvement operation, a power conversion unit (28) is instructed to stop the operation after a predetermined time has elapsed, so that the power conversion unit (28) The power factor improvement unit (25) can suppress the increase in the output voltage of the power factor improvement unit (25) even if it takes longer time to stop after receiving the instruction to stop. it can.

  In the power converter of the third invention, in the second invention, the power factor improving section (25) is connected in series to the reactor (L25a, L25b, L25c) and the reactor (L25a, L25b, L25c). Switching elements (Q25a, Q25b, Q25c). The switching element (Q25a, Q25b, Q25c) stops the switching operation at least after the control unit (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation for the predetermined time. It is time to do.

  According to this, after instructing the power factor improvement unit (25) to stop the power factor improvement operation, at least after the time until the switching element (Q25a, Q25b, Q25c) stops the switching operation has elapsed, Instructs the power converter (28) to stop the operation. For this reason, it is possible to more reliably perform the operation of the power conversion unit (28) after the power factor improvement unit (25) stops the power factor improvement operation.

  In the power converter of the fourth invention, in the first invention, the control unit (31) improves the power factor of the power factor improvement unit (25) by lowering the output voltage of the power factor improvement unit (25). After detecting the stop of the operation, the power converter (28) is instructed to stop the operation.

  According to this, since the control unit (31) detects the stop of the power factor improvement operation of the power factor improvement unit (25) by the decrease in the output voltage of the power factor improvement unit (25), the power factor improvement unit (25) It is possible to more reliably perform the power converter (28) to stop the operation after stopping the power factor correction operation.

  In the power converter of the fifth invention, in the first invention, the control unit (31) is driven when an overcurrent flows through the power converter (28) or is driven by the power converter (28). If the discharge pressure of the compressor (72) as a device exceeds a threshold, the power conversion unit (28) is instructed before the power factor improvement unit (25) is instructed to stop the power factor improvement operation. To stop the operation.

  When an overcurrent flows through the power converter (28) or when the discharge pressure of the compressor (72) exceeds a threshold value, it is necessary to urgently stop the motor driven by the power converter (28). is there. According to the fifth aspect, in such a case, the control unit (31) can quickly stop the operation of the power conversion unit (28).

  In the power converter of 6th invention, in 1st invention, between the said rectification | straightening part (22) and the said power factor improvement part (25), or the said alternating current power supply (91) and the said rectification | straightening part (22) It further has a switch (23) for controlling conduction between the two. When an overcurrent flows through the power converter (28), or when the discharge pressure of the compressor (72) as a device driven by the power converter (28) exceeds a threshold value, the switch ( 23) turns off.

  When an overcurrent flows through the power converter (28) or when the discharge pressure of the compressor (72) exceeds a threshold value, it is necessary to urgently stop the motor driven by the power converter (28). is there. According to the sixth invention, in such a case, the operation of the power converter (28) can be quickly stopped by turning off the switch (23).

  An air conditioner according to a seventh aspect includes any one of the power converters according to the first to sixth aspects.

  According to this, in the air conditioner, an increase in the output voltage of the power factor improvement unit (25) can be suppressed. The voltage applied to the switching elements of the power factor improving unit and the smoothing capacitor can be suppressed, and the possibility of failure of these elements can be suppressed while suppressing the withstand voltage of these elements.

  According to the first to seventh inventions, it is possible to suppress the possibility of failure of these elements while suppressing the pressure resistance of the elements of the power factor improvement unit. Since it is not necessary to increase the pressure resistance of the element, it is possible to reduce the size and cost of the element.

FIG. 1 is a configuration diagram of a motor drive system including a power conversion device according to an embodiment of the present invention. FIG. 2 is a schematic diagram of the configuration of the air conditioner. FIG. 3 is a timing chart showing the change over time of the input voltage, its peak value, the input-side detection cycle, and the detection result of the input voltage detector. FIG. 4 is a diagram schematically illustrating a functional unit of the controller of FIG. FIG. 5 is a graph showing an example of a signal waveform and the like in the power conversion device (20) of FIG. FIG. 6 is a graph showing an example of states of the power conversion unit (28) and the power factor improvement unit (25) when the control as shown in FIG. 5 is performed. FIG. 7 is a graph showing an example of states of the power conversion unit (28) and the power factor improvement unit (25) when the delay time (TD) in FIG. 5 is zero.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Components shown with the same reference numbers in the drawings are identical or similar components. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

<Overview>
FIG. 1 is a configuration diagram of a motor drive system (100) including a power conversion device (20) according to an embodiment of the present invention. The motor drive system (100) in FIG. 1 includes a motor (11) and a power converter (20).

  The motor (11) is a three-phase brushless DC motor, and has a stator, a rotor, a hall element and the like, although not shown. The stator has a plurality of drive coils. The rotor has a permanent magnet. The hall element is an element for detecting the position of the rotor with respect to the stator.

  The motor (11) is, for example, a drive source for a compressor included in the air conditioner. Therefore, the motor drive system (100) may be mounted on the air conditioner.

  FIG. 2 is a schematic diagram of the configuration of the air conditioner (70). The motor (11) in FIG. 1 is, for example, a drive source for a compressor (72) included in the air conditioner (70) in FIG. As shown in FIG. 2, the outdoor unit (71) includes a compressor (72) and a motor (11) for compressing the refrigerant, a four-way switching valve (73) for switching the flow of the refrigerant, and between the outside air and the refrigerant. Outdoor heat exchanger (74) for exchanging heat in the room, expansion valve (75) for decompressing the refrigerant, outdoor fan (76) for supplying outside air to the outdoor heat exchanger (74), fan motor (77), and pressure sensor (79) is included. The indoor unit (80) includes an indoor heat exchanger (81) for exchanging heat between indoor air and refrigerant, an indoor fan (82) and a fan motor (83) for blowing the air after heat exchange into the room. include.

  The power converter (20) is connected to the commercial power supply (91) and the motor (11) via a plurality of harnesses. The power converter (20) converts input AC from a commercial power source (91), which is AC power, into output AC power (SU, SV, SW) and supplies it to the motor (11). Thereby, the motor (11) can be driven.

  In the present embodiment, a case where the commercial power source (91) is a single-phase power source is taken as an example.

<Configuration of power converter>
The power converter (20) includes a filter (21), a rectifier (22), a main power relay (23), an input voltage detector (24), a power factor corrector (25), an output voltage detector (27), It has a power converter (28), a current detector (29), and a controller (controller) (31).

-Filter-
The filter (21) is located between the commercial power supply (91) and the rectifying unit (22). The filter (21) is a low-pass filter composed of a coil (21a) and a capacitor (21b), and is a commercial power source for high-frequency noise generated in the power factor improvement unit (25) and the power conversion unit (28). (91) Prevents wraparound.

-Rectifier-
The rectifying unit (22) is connected to the subsequent stage of the filter (21). The rectification unit (22) includes four diodes (22a, 22b, 22c, 22d).

  Specifically, the cathode terminals of the diodes (22a, 22c) are connected to the power supply wiring (41). The anode terminals of the diodes (22b, 22d) are connected to the GND wiring (42). The connection point between the anode terminal of the diode (22a) and the cathode terminal of the diode (22b), and the connection point between the anode terminal of the diode (22c) and the cathode terminal of the diode (22d) are respectively the commercial power supply (91). Connected to the output.

  The rectification unit (22) performs full-wave rectification on the alternating current input from the commercial power supply (91) as shown in FIG. FIG. 3 shows a rectified voltage (hereinafter referred to as input voltage) (V1), a peak value (V11) of the input voltage (V1), an input side detection cycle described later, and a detection result (Vac_peak) of the input voltage detection unit (24). ) Over time.

  Hereinafter, for convenience of explanation, the input AC voltage is referred to as “commercial voltage (V0)”.

−Main power relay−
The main power supply relay (23) is connected in series on the power supply wiring (41) between the rectification unit (22) and the power factor improvement unit (25). The main power relay (23) is a normally closed contact. The main power supply relay (23) is opened when, for example, the drive of the motor (11) must be stopped urgently, thereby cutting off the power supply from the commercial power supply (91) to the motor (11) side.

  Examples of cases where the drive of the motor (11) must be urgently stopped include a case where a high voltage abnormality has occurred in the compressor (72) and a case where an excessive current flows through the motor (11).

  Note that the position of the main power supply relay (23) may be the front stage instead of the rear stage of the rectification unit (22).

−Input voltage detector−
The input voltage detector (24) detects the voltage (V1) output from the rectifier (22) as the input voltage of the power factor corrector (25).

  Specifically, as shown in FIGS. 1 and 4, the input voltage detector (24) mainly includes two resistors (24a, 24b) connected in series, a peak hold circuit (24c), and input voltage sampling. It is comprised by the controller (31) etc. which function as a part (31a). Two resistors (24a, 24b) connected in series with each other are connected to both ends of the output of the rectifying unit (22) between the main power relay (23) and the power factor improving unit (25). The voltage value at the connection point between the resistors (24a, 24b) is input to the peak hold circuit (24c). In the peak hold circuit (24c), as shown in FIG. 3, the peak value (V11) which is the maximum value of the input voltage (V1) is maintained for a fixed time. This peak value (V11) is input to the controller (31), and is sampled and AD-converted by the input voltage sampling unit (31a) at the input side detection period as shown in FIG. 3, and is recognized as a detection result (Vac_peak). The

  Here, FIG. 4 is a diagram schematically showing a functional unit of the controller (31) of FIG.

  FIG. 3 shows a case where the input-side detection cycle, which is the detection cycle of the input voltage detector (24), is longer than the cycle (power supply frequency) at which the input voltage (V1) takes the maximum value.

-Power factor improvement section-
As shown in FIG. 1, the power factor improvement part (25) is connected to the output of the rectification part (22) via the main power supply relay (23). The power factor improvement unit (25) is a boost type power factor improvement circuit, and performs a power factor improvement operation by boosting and smoothing the input voltage (V1).

  Specifically, the power factor improvement unit (25) in FIG. 1 includes a power factor improvement drive unit (30), a three-phase boost chopper circuit configured to be able to perform a three-phase interleaved operation, And two smoothing capacitors (26). Specifically, the power factor improvement unit (25) includes three reactors (L25a, L25b, L25c), three switching elements (Q25a, Q25b, Q25c), three resistors (R25a, R25b, R25c), and three diodes. (D25a, D25b, D25c) and one smoothing capacitor (26).

  One end of the reactor (L25a) is connected to the main power relay (23), and the input voltage (V1) is used as electric energy, and this is changed into magnetic flux energy and stored. The inductance value of the reactor (L25a) is appropriately determined according to the value of the current flowing on the power supply wiring (41), the switching frequency of the switching element (Q25a), and the like.

  The switching element (Q25a) is composed of an Nch insulated gate bipolar transistor, and is connected to the other end of the reactor (L25a). The switching element (Q25a) plays a role of switching between accumulation and discharge of energy based on the input voltage (V1) in the reactor (L25a). The switching element (Q25a) is controlled to be turned on and off by the power factor correction drive unit (30).

  The resistor (R25a) is a shunt resistor for detecting a power factor correction (PFC) current (Ipfc) flowing in the switching element (Q25a), and is a resistance between the switching element (Q25a) and the GND wiring (42). Connected between. The voltage (Vd1) of the resistor (R25a) is input to the controller (31) functioning as the PFC current calculation unit (31b) after AD conversion (see FIG. 4), and is used to calculate the PFC current (Ipfc). The PFC current (Ipfc) is used for drive control of the power factor improvement unit (25). This is because even if the output voltage (V2) fluctuates to some extent, stable energy is supplied to the subsequent stage of the power factor improvement unit (25). The resistance value of the resistor (R25a) is determined to be an appropriate value that does not hinder the voltage boosting operation by the power factor correction section (25).

  In FIG. 1, only the voltage (Vd1) of the resistor (R25c) is input to the controller (31), but the voltage (Vd1) of the resistors (R25a, R25b) is also input to the controller (31).

  The diode (D25a) is connected in series on the power supply wiring (41) on the output side of the reactor (L25a). In particular, the anode terminal of the diode (D25a) is connected downstream of the connection point between the reactor (L25a) and the switching element (Q25a) in the current flow direction. The diode (D25a) allows only a current flow from the reactor (L25a) side to the power conversion unit (28) side.

  The smoothing capacitor (26) is composed of, for example, an electrolytic capacitor, and one smoothing capacitor (26) is provided in common for the boost chopper circuit of each phase. The smoothing capacitor (26) is connected in parallel to each switching element (Q25a, Q25b, Q25c) on the output side of each reactor (L25a, L25b, L25c). The smoothing capacitor (26) charges and discharges energy released from each reactor (L25a, L25b, L25c), thereby generating a DC voltage with a relatively low ripple component.

  The power factor correction drive unit (30) is connected to the gate terminal of each switching element (Q25a, Q25b, Q25c) and the controller (31). The power factor correction drive unit (30) is configured by, for example, an integrated circuit. Based on the PFC drive command signal (Cpfc) from the controller (31), the power factor correction drive unit (30) controls the application of the gate voltage to each switching element (Q25a, Q25b, Q25c). Controls the power factor improving operation of the rate improving unit (25).

  Specifically, the power factor improvement drive unit (30) turns on and off each switching element (Q25a, Q25b, Q25c) in a short period when the power factor improvement unit (25) performs the power factor improvement operation. The gate control signals (G1, G2, G3) to be repeated in the above are output to the switching elements (Q25a, Q25b, Q25c). Conversely, the power factor improvement drive unit (30) keeps all the switching elements (Q25a, Q25b, Q25c) in the off state when the power factor improvement unit (25) does not perform the power factor improvement operation. Gate control signals (G1, G2, G3) are output to the switching elements (Q25a, Q25b, Q25c).

  The boosting operation (that is, the power factor improving operation) of the power factor improving unit (25) will be described taking a boosting chopper circuit for one phase as an example. First, when the switching element (Q25a) is turned on, a current path is formed from the power supply wiring (41) to the GND wiring (42) through the reactor (L25a), the switching element (Q25a), and the resistor (R25a), and the PFC current ( Ipfc) flows in this order. Then, the PFC current (Ipfc) flows through the reactor (L25a), so that energy is accumulated in the reactor (L25a). Next, when the switching element (Q25a) is turned off, the current path is cut off by the switching element (Q25a). The current corresponding to the energy accumulated in the reactor (L25a) flows into the smoothing capacitor (26) through the diode (D25a), and the voltage of the smoothing capacitor (26) increases.

  The other two-phase boost chopper circuits are connected in parallel with the above-described one-phase boost chopper circuit, and the operation is the same as described above.

  The number of components (reactors (L25a, L25b, L25c), etc.) of the power factor improvement unit (25) is an example, and is not limited to the above. Further, instead of the resistors (R25a, R25b, R25c), a current sensor (not shown) may detect the PFC current (Ipfc).

−Output voltage detector−
The output voltage detector (27) detects the output voltage (V2).

  As shown in FIGS. 1 and 4, the output voltage detection unit (27) mainly includes two resistors (27a, 27b) connected in series with each other, and a controller (31) that functions as an output voltage sampling unit (31c). It is constituted by. The two resistors (27a, 27b) connected in series with each other are connected to both ends of the smoothing capacitor (26) between the power factor improvement unit (25) and the power conversion unit (28). The voltage (V21) at the connection point between the resistors (27a, 27b) is input to the controller (31), sampled and AD-converted by the output voltage sampling unit (31c) at the output side detection period, and the output voltage (V2) Recognized as a detection result (Vdc).

  The output-side detection cycle may be shorter than the input-side detection cycle that is the detection cycle of the input voltage detector (24). As an example, when the input side detection period is about 1 sec, the output side detection period may be about 10 msec.

-Power converter-
The power conversion unit (28) is connected in parallel to the reactor (L25a, L25b, L25c) on the output side of the power factor improvement unit (25). When the output voltage (V2) is supplied from the power factor improvement unit (25), the power conversion unit (28) generates output AC power (SU, SV, SW).

  Although not shown, the power conversion unit (28) includes an inverter circuit and an inverter drive unit. The inverter circuit is configured to have a plurality of power elements each composed of, for example, an insulated gate bipolar transistor, and a plurality of freewheeling diodes connected in antiparallel to the power elements. The inverter drive part is comprised, for example by the integrated circuit, and is connected to the gate terminal of each power element. Based on the motor control signal (Pwm) output from the controller (31), the inverter drive unit turns on and off each power element by controlling the application of the gate voltage to each power element, and the inverter circuit Output AC power (SU, SV, SW) is generated.

-Current detector-
The current detection unit (29) detects the value of the input current (Im) to the power conversion unit (28). The input current (Im) flows from the commercial power supply (91) to the power supply wiring (41), the power conversion unit (28), and the motor (11), and again passes through the power conversion unit (28) and the GND wiring (42). The current that flows into the power factor correction section (25).

  As shown in FIGS. 1 and 4, the current detection unit (29) is mainly a controller that functions as a shunt resistor (29a) and an input current calculation unit (31d) connected in series on the GND wiring (42). 31) etc. The voltage (Vd2) of the shunt resistor (29a) is input to the controller (31), sampled and AD converted at a predetermined sampling period by the input current calculation unit (31d), and used to calculate the input current (Im). The

-Controller-
The controller (31) includes a memory and a CPU. As shown in FIG. 4, the controller (31), according to various programs stored in the memory, has the input voltage sampling unit (31a), the PFC current calculation unit (31b), the output voltage sampling unit (31c), In addition to the input current calculator (31d), it functions as a motor drive controller (31e) and a power factor correction controller (31f).

  A motor drive control part (31e) determines a motor control signal (Pwm) based on the rotor position information in a motor (11), and outputs this to the inverter drive part of a power converter (28). The rotor position information includes the detection result of the Hall element in the motor (11), the input current (Im) that is the detection result of the current detection unit (29), and the like. Further, the motor drive control unit (31e) uses the rotor position information and the detection results (Vac_peak, Vdc) of the respective detection units (24, 27) at times while the motor (11) is driven, Feedback control is performed for driving the motor (11).

  Further, the power factor improvement control unit (31f) performs control related to the power factor improvement unit (25). The control includes on / off control of the power factor improvement operation of the power factor improvement unit (25) during normal rotation of the motor (11), and the target of the output voltage (Vdc) that the power factor improvement unit (25) should output. Examples include variable control of the output target value (Vdc_ref), which is a value, and on / off control of the power factor improvement operation of the power factor improvement unit (25) accompanying the occurrence of an instantaneous voltage drop or an instantaneous power failure.

  On / off control of the power factor correction operation of the power factor improvement unit (25) during normal rotation of the motor (11) refers to the input current (Im), etc. when there is no instantaneous voltage drop or instantaneous power failure Based on the control of the power factor improvement operation. In the control, for example, when the input current (Im) exceeds the first threshold value, the power factor improvement unit (25) performs the power factor improvement operation, and the second threshold value where the input current (Im) is smaller than the first threshold value. If it falls below, the power factor improvement unit (25) does not perform the power factor improvement operation. In addition, in the said control, it replaces with the control method by input current (Im), the control method by the magnitude of the output power of a power factor improvement part (25), and a motor (11) is started, and a power factor improvement part (25) A control method that causes the power factor correction operation to be performed may be employed.

  Below, the control in a power converter device (20) when stopping the driving | operation of the apparatus driven by a power converter part (28) is explained in full detail.

<Control in power conversion device when stopping operation of driven device>
FIG. 5 is a graph showing an example of a signal waveform and the like in the power conversion device (20) of FIG. At time (T11), the controller (31) asserts the main power control signal (Cs) that controls the main power relay (23) and the motor control signal (Pwm) that controls the operation of the power converter (28). To do. Then, the main power supply relay (23) is turned on, the power converter (28) starts the switching operation, and the operation of the motor (11) is started. Thereafter, the input current (Im) to the power converter (28) increases and reaches a threshold value at time (T12). Then, the controller (31) asserts the PFC drive command signal (Cpfc), and the power factor improvement unit (25) starts the power factor improvement operation.

  Next, the controller (31) stops the operation of the motor (11) as a device driven by the power converter (28). At this time, the controller (31) instructs the power conversion unit (25) to stop the operation after instructing the power factor improvement unit (25) to stop the power factor improvement operation. Specifically, the controller (31) first negates the PFC drive command signal (Cpfc) at time (T13), and then the motor control signal (Pwm) at time (T14) after a predetermined delay time (TD) has elapsed. ). When the motor control signal (Pwm) is negated, the motor (11) stops.

  Thereafter, the power conversion device (20) repeats the same operation from time (T15) to time (T18). At time (T28), the controller (31) negates the main power control signal (Cs). Then, the main power supply relay (23) is turned off, and the entire operation of the power converter (20) is stopped. Note that the main power control signal (Cs) is negated because the controller (31) receives a motor stop command, or the motor is stopped urgently due to an overcurrent flowing through the power converter (28), etc. This is not because the operation and stop of the motor (11) are repeated.

  FIG. 6 is a graph showing an example of states of the power conversion unit (28) and the power factor improvement unit (25) when the control as shown in FIG. 5 is performed. At time (T31), the power factor improvement unit (25) starts to operate according to the PFC drive command signal (Cpfc). Then, the output voltage (V2) of the power factor improvement unit (25) reaches its target value (Vdc_ref) by the power factor improvement operation of the power factor improvement unit (25).

  Thereafter, the controller (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation. At time (T32), the power factor correction unit (25) stops operating. At this time, since the power converter (28) is operating, the output voltage (V2) starts to decrease. Thereafter, the controller (31) instructs the power conversion unit (28) to stop the operation, and the power conversion unit (28) stops the operation.

  Here, after the power factor improvement unit (25) stops operating, the power conversion unit (28) needs to stop operating. Also, after the controller (31) gives an instruction to the power factor correction unit (25) by the PFC drive command signal (Cpfc), until the switching element (Q25a, Q25b, Q25c) actually stops the switching operation, It takes a certain amount of time.

  Therefore, the delay time (TD) in FIG. 5 is at least switched by the switching elements (Q25a, Q25b, Q25c) after the controller (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation. This is the time until the operation stops. Specifically, the delay time (TD) is determined by the switching elements (Q25a, Q25b, Q25c) according to this signal after receiving the PFC drive command signal (Cpfc) negated by the power factor correction drive unit (30). Delay time until the gate control signal (G1, G2, G3) is output, and switching after the switching element (Q25a, Q25b, Q25c) receives the gate control signal (G1, G2, G3) This is the sum of the delay time until the operation is stopped.

  For comparison, an example in another case will be described. FIG. 7 is a graph showing an example of states of the power conversion unit (28) and the power factor improvement unit (25) when the delay time (TD) in FIG. 5 is zero. In other words, FIG. 7 is a graph in a case where instructions to stop the operation are simultaneously given to the power factor improvement unit (25) and the power conversion unit (28).

  At time (T41), the power factor improvement unit (25) starts to operate according to the PFC drive command signal (Cpfc). Then, the output voltage (V2) of the power factor improvement unit (25) reaches its target value (Vdc_ref) by the power factor improvement operation of the power factor improvement unit (25).

  Thereafter, the controller (31) simultaneously instructs the power factor improvement unit (25) and the power conversion unit (28) to stop the operation. Since the power factor improvement unit (25) has the power factor improvement drive unit (30), the time from when the signal for instructing to stop to when it actually stops is the power conversion unit (28) Longer. For this reason, at time (T42), first, the power conversion unit (28) stops its operation.

  At this time, the power factor improving unit (25) is still performing the power factor improving operation. However, because the load is gone, the power factor improvement unit (25) cannot follow the sudden change in load, and the output voltage (V2) of the power factor improvement unit (25) is more transient than its target value (Vdc_ref). Will rise. Thereafter, the power factor correction unit (25) stops operating, and the output voltage (V2) decreases. Since the output voltage (V2) of the power factor improvement unit (25) is higher than the target value (Vdc_ref), the switching elements (Q25a, Q25b, Q25c) and smoothing capacitors (26) of the power factor improvement unit (25) In addition, a higher voltage than usual is applied, and the possibility of failure of these elements due to overvoltage increases.

  In this embodiment, as shown in FIG. 5, the controller (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation, and then instructs the power conversion unit (28) to stop the operation. To do. Thereby, it is possible to avoid the output voltage (V2) from rising too much as shown in FIG. For this reason, it is possible to prevent the voltage applied to the switching elements (Q25a, Q25b, Q25c) and the smoothing capacitor (26) of the power factor improving section (25) from becoming too high.

  The case where the power conversion unit (28) stops operating after the power factor improving unit (25) stops operating by setting the delay time (TD) has been described. However, the controller (31) is not limited to this, and the controller (31) determines the power of the power factor improvement unit (25) based on the output voltage (V2) of the power factor improvement unit (25) (or a voltage obtained by dividing the output voltage (V21)). After detecting the stop of the rate improvement operation, the power conversion unit (28) may be instructed to stop the operation. Specifically, the controller (31) detects the power of the power factor improvement unit (25) when, for example, the power factor improvement unit (25) stops operating and the output voltage (V2) decreases by a predetermined voltage. The stop of the rate improvement operation may be detected.

  In an emergency, it is necessary to stop the motor (11) as soon as possible. Therefore, in an emergency, the controller (31) instructs the power conversion unit (28) to stop the operation before instructing the power factor improvement unit (25) to stop the power factor improvement operation. Also good. The case of emergency is, for example, when an overcurrent flows through the power converter (28) or when the discharge pressure of the compressor (72) as a device driven by the power converter (28) exceeds a threshold value It is. In an emergency, the main power relay (23) as a switch for controlling conduction between the rectifying unit (22) and the power factor improving unit (25) in FIG. 1 may be turned off. The power converter (20) replaces the main power supply relay (23) of FIG. 1 with the main power supply relay (23) as a switch for controlling conduction between the AC power supply (91) and the rectifying unit (22). You may have. The main power relay (23) may also be turned off in an emergency.

  The controller (31) measures the input current (Im) to the power converter (28) by the voltage (Vd2) of the shunt resistor (29a), so that an overcurrent has flowed through the power converter (28). Can be detected. When the controller (31) detects that an overcurrent has flowed into the power conversion unit (28), the controller (31) before instructing the power factor improvement unit (25) to stop the power factor improvement operation, the power conversion unit (28) May be instructed to stop the operation, or the main power relay (23) may be turned off.

  The power converter (20) may further include a current measuring unit that measures the input current (Im). When the current measurement unit detects that an overcurrent has flowed to the power conversion unit (28), the current measurement unit notifies the controller (31) of this by an interrupt, for example.

  The pressure sensor (79) is connected to piping on the discharge side of the compressor (72), and measures the discharge pressure of the compressor (72). The pressure sensor (79) turns off the main power supply relay (23) by a high voltage signal (Cp) when the discharge pressure exceeds the threshold value. The main power supply relay (23) notifies the controller (31), for example, by interruption that the discharge pressure has exceeded the threshold value. Upon receiving the notification, the controller (31) may instruct the power conversion unit (28) to stop the operation before instructing the power factor improvement unit (25) to stop the power factor improvement operation.

<Effect of embodiment>
As described above, since the power factor improvement unit (25) is instructed to stop the power factor improvement operation and then the power conversion unit (28) is instructed to stop the operation, the power factor improvement unit (25) An increase in output voltage can be suppressed. Since the voltage applied to the switching elements (Q25a, Q25b, Q25c) of the power factor improvement unit (25) and the smoothing capacitor (26) can be suppressed, these elements fail while suppressing the pressure resistance of these elements. The possibility can be suppressed.

  As described above, the present invention is useful for a power conversion device having a boost type power factor correction unit, an air conditioner having the same, and the like.

20 Power converter
22 Rectifier
23 Main power relay (switch)
25 Power factor improvement department
28 Power converter
31 Controller (Controller)
70 Air conditioner
72 Compressor
L25a, L25b, L25c reactor
Q25a, Q25b, Q25c Switching element
V1 input voltage
V2 output voltage

  The present invention relates to a power converter and an air conditioner having a power factor improving unit, and more particularly to control when stopping the operation of a device driven by the power converter.

  Generally, a compressor in an air conditioner uses a motor as a drive source. AC power is supplied to the motor from the power converter.

  As a power conversion device, as disclosed in Patent Document 1, a device mainly composed of a rectification unit, a step-up power factor correction unit, and an inverter type power conversion unit is generally known. First, the AC commercial voltage output from the commercial power source is rectified by the rectification unit. The rectified voltage is boosted to a desired voltage by the power factor improving unit and smoothed, whereby the power factor is improved. The voltage after the power factor improvement is supplied to the power conversion unit. The power conversion unit generates AC power for driving the motor using the voltage after the power factor is improved.

JP 2011-239547 A

  The power factor improving unit performs a switching operation so that the output voltage is maintained at a set value. However, when the power conversion unit stops, the load decreases rapidly, so that the control of the power factor improvement unit cannot follow, and the output voltage of the power factor improvement unit may suddenly increase. Then, a higher voltage than usual is applied to the switching element of the power factor correction unit and the smoothing capacitor.

  If a switching element or a smoothing capacitor that can withstand overvoltage is used, failure due to overvoltage can be avoided. However, if it does so, an element will enlarge and cost will also rise.

  An object of the present invention is to suppress the possibility of failure of these elements while suppressing the pressure resistance of the elements of the power factor improvement unit.

A power conversion device according to a first aspect of the present invention includes a rectifying unit (22) for rectifying an input AC from an AC power source (91), and a power factor improvement for an input voltage (V1) output from the rectifying unit (22). A power factor improvement unit (25) that performs an operation, a power conversion unit (28) that is connected to an output of the power factor improvement unit (25) and generates output AC power, and a power factor improvement unit (25) And a control unit (31) for controlling the power factor correction operation. The power factor improving unit (25) includes a reactor (L25a, L25b, L25c) and a switching element (Q25a, Q25b, Q25c) connected in series to the reactor (L25a, L25b, L25c). When the control unit (31) stops the operation of the device driven by the power conversion unit (28), the control unit (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation for a predetermined time. After the elapse, the power converter (28) is instructed to stop the operation. The switching element (Q25a, Q25b, Q25c) stops the switching operation at least after the control unit (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation for the predetermined time. It is time to do.

  According to this, since the power factor improvement unit (25) is instructed to stop the power factor improvement operation and then the power conversion unit (28) is instructed to stop the operation, the output of the power factor improvement unit (25) An increase in voltage can be suppressed. The voltage applied to the switching elements of the power factor improving unit and the smoothing capacitor can be suppressed, and the possibility of failure of these elements can be suppressed while suppressing the withstand voltage of these elements.

Since the power factor improvement unit (25) is instructed to stop the power factor correction operation, the power conversion unit (28) is instructed to stop the operation after a predetermined time has elapsed, so the power factor is higher than the power conversion unit (28). Even when the improvement unit (25) has a longer time from receiving the instruction to stop until it stops, it is possible to suppress an increase in the output voltage of the power factor improvement unit (25).

After instructing the power factor correction unit (25) to stop the power factor correction operation, at least after the time until the switching elements (Q25a, Q25b, Q25c) stop switching operation, the power conversion unit ( Instruct 28) to stop operation. For this reason, it is possible to more reliably perform the operation of the power conversion unit (28) after the power factor improvement unit (25) stops the power factor improvement operation.

The power conversion device of the second invention is a power factor improvement for a rectifying unit (22) for rectifying an input AC from an AC power source (91) and an input voltage (V1) output from the rectifying unit (22). A power factor improvement unit (25) that performs an operation, a power conversion unit (28) that is connected to an output of the power factor improvement unit (25) and generates output AC power, and a power factor improvement unit (25) And a control unit (31) for controlling the power factor correction operation. When stopping the operation of the device driven by the power conversion unit (28) , the control unit (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation, and the power factor After detecting the stop of the power factor improvement operation of the power factor improvement unit (25) due to the decrease of the output voltage of the improvement unit (25), the power conversion unit (28) is instructed to stop the operation.

  According to this, since the control unit (31) detects the stop of the power factor improvement operation of the power factor improvement unit (25) by the decrease in the output voltage of the power factor improvement unit (25), the power factor improvement unit (25) It is possible to more reliably perform the power converter (28) to stop the operation after stopping the power factor correction operation.

In the power conversion device according to the third aspect of the present invention, in the first or second aspect of the invention, the control unit (31) causes the overcurrent to flow through the power conversion unit (28) or the power conversion unit (28). When the discharge pressure of the compressor (72) as a device driven by the power exceeds the threshold, before instructing the power factor improvement unit (25) to stop the power factor improvement operation, the power conversion unit Instruct (28) to stop the operation.

  When an overcurrent flows through the power converter (28) or when the discharge pressure of the compressor (72) exceeds a threshold value, it is necessary to urgently stop the motor driven by the power converter (28). is there. According to the fifth aspect, in such a case, the control unit (31) can quickly stop the operation of the power conversion unit (28).

In the power conversion device of the fourth invention, in the first or second invention, between the rectifying unit (22) and the power factor improving unit (25), or the AC power source (91) and the rectifying unit ( The switch (23) which controls conduction | electrical_connection between 22) is further provided. When an overcurrent flows through the power converter (28), or when the discharge pressure of the compressor (72) as a device driven by the power converter (28) exceeds a threshold value, the switch ( 23) turns off.

  When an overcurrent flows through the power converter (28) or when the discharge pressure of the compressor (72) exceeds a threshold value, it is necessary to urgently stop the motor driven by the power converter (28). is there. According to the sixth invention, in such a case, the operation of the power converter (28) can be quickly stopped by turning off the switch (23).

An air conditioner of a fifth invention has any one of the power conversion devices of the first to fourth inventions.

  According to this, in the air conditioner, an increase in the output voltage of the power factor improvement unit (25) can be suppressed. The voltage applied to the switching elements of the power factor improving unit and the smoothing capacitor can be suppressed, and the possibility of failure of these elements can be suppressed while suppressing the withstand voltage of these elements.

According to the first to fifth inventions, it is possible to suppress the possibility of failure of these elements while suppressing the pressure resistance of the elements of the power factor improvement unit. Since it is not necessary to increase the pressure resistance of the element, it is possible to reduce the size and cost of the element.

FIG. 1 is a configuration diagram of a motor drive system including a power conversion device according to an embodiment of the present invention. FIG. 2 is a schematic diagram of the configuration of the air conditioner. FIG. 3 is a timing chart showing the change over time of the input voltage, its peak value, the input-side detection cycle, and the detection result of the input voltage detector. FIG. 4 is a diagram schematically illustrating a functional unit of the controller of FIG. FIG. 5 is a graph showing an example of a signal waveform and the like in the power conversion device (20) of FIG. FIG. 6 is a graph showing an example of states of the power conversion unit (28) and the power factor improvement unit (25) when the control as shown in FIG. 5 is performed. FIG. 7 is a graph showing an example of states of the power conversion unit (28) and the power factor improvement unit (25) when the delay time (TD) in FIG. 5 is zero.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Components shown with the same reference numbers in the drawings are identical or similar components. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

<Overview>
FIG. 1 is a configuration diagram of a motor drive system (100) including a power conversion device (20) according to an embodiment of the present invention. The motor drive system (100) in FIG. 1 includes a motor (11) and a power converter (20).

  The motor (11) is a three-phase brushless DC motor, and has a stator, a rotor, a hall element and the like, although not shown. The stator has a plurality of drive coils. The rotor has a permanent magnet. The hall element is an element for detecting the position of the rotor with respect to the stator.

  The motor (11) is, for example, a drive source for a compressor included in the air conditioner. Therefore, the motor drive system (100) may be mounted on the air conditioner.

  FIG. 2 is a schematic diagram of the configuration of the air conditioner (70). The motor (11) in FIG. 1 is, for example, a drive source for a compressor (72) included in the air conditioner (70) in FIG. As shown in FIG. 2, the outdoor unit (71) includes a compressor (72) and a motor (11) for compressing the refrigerant, a four-way switching valve (73) for switching the flow of the refrigerant, and between the outside air and the refrigerant. Outdoor heat exchanger (74) for exchanging heat in the room, expansion valve (75) for decompressing the refrigerant, outdoor fan (76) for supplying outside air to the outdoor heat exchanger (74), fan motor (77), and pressure sensor (79) is included. The indoor unit (80) includes an indoor heat exchanger (81) for exchanging heat between indoor air and refrigerant, an indoor fan (82) and a fan motor (83) for blowing the air after heat exchange into the room. include.

  The power converter (20) is connected to the commercial power supply (91) and the motor (11) via a plurality of harnesses. The power converter (20) converts input AC from a commercial power source (91), which is AC power, into output AC power (SU, SV, SW) and supplies it to the motor (11). Thereby, the motor (11) can be driven.

  In the present embodiment, a case where the commercial power source (91) is a single-phase power source is taken as an example.

<Configuration of power converter>
The power converter (20) includes a filter (21), a rectifier (22), a main power relay (23), an input voltage detector (24), a power factor corrector (25), an output voltage detector (27), It has a power converter (28), a current detector (29), and a controller (controller) (31).

-Filter-
The filter (21) is located between the commercial power supply (91) and the rectifying unit (22). The filter (21) is a low-pass filter composed of a coil (21a) and a capacitor (21b), and is a commercial power source for high-frequency noise generated in the power factor improvement unit (25) and the power conversion unit (28). (91) Prevents wraparound.

-Rectifier-
The rectifying unit (22) is connected to the subsequent stage of the filter (21). The rectification unit (22) includes four diodes (22a, 22b, 22c, 22d).

  Specifically, the cathode terminals of the diodes (22a, 22c) are connected to the power supply wiring (41). The anode terminals of the diodes (22b, 22d) are connected to the GND wiring (42). The connection point between the anode terminal of the diode (22a) and the cathode terminal of the diode (22b), and the connection point between the anode terminal of the diode (22c) and the cathode terminal of the diode (22d) are respectively the commercial power supply (91). Connected to the output.

  The rectification unit (22) performs full-wave rectification on the alternating current input from the commercial power supply (91) as shown in FIG. FIG. 3 shows a rectified voltage (hereinafter referred to as input voltage) (V1), a peak value (V11) of the input voltage (V1), an input side detection cycle described later, and a detection result (Vac_peak) of the input voltage detection unit (24). ) Over time.

  Hereinafter, for convenience of explanation, the input AC voltage is referred to as “commercial voltage (V0)”.

−Main power relay−
The main power supply relay (23) is connected in series on the power supply wiring (41) between the rectification unit (22) and the power factor improvement unit (25). The main power relay (23) is a normally closed contact. The main power supply relay (23) is opened when, for example, the drive of the motor (11) must be stopped urgently, thereby cutting off the power supply from the commercial power supply (91) to the motor (11) side.

  Examples of cases where the drive of the motor (11) must be urgently stopped include a case where a high voltage abnormality has occurred in the compressor (72) and a case where an excessive current flows through the motor (11).

  Note that the position of the main power supply relay (23) may be the front stage instead of the rear stage of the rectification unit (22).

−Input voltage detector−
The input voltage detector (24) detects the voltage (V1) output from the rectifier (22) as the input voltage of the power factor corrector (25).

  Specifically, as shown in FIGS. 1 and 4, the input voltage detector (24) mainly includes two resistors (24a, 24b) connected in series, a peak hold circuit (24c), and input voltage sampling. It is comprised by the controller (31) etc. which function as a part (31a). Two resistors (24a, 24b) connected in series with each other are connected to both ends of the output of the rectifying unit (22) between the main power relay (23) and the power factor improving unit (25). The voltage value at the connection point between the resistors (24a, 24b) is input to the peak hold circuit (24c). In the peak hold circuit (24c), as shown in FIG. 3, the peak value (V11) which is the maximum value of the input voltage (V1) is maintained for a fixed time. This peak value (V11) is input to the controller (31), and is sampled and AD-converted by the input voltage sampling unit (31a) at the input side detection period as shown in FIG. 3, and is recognized as a detection result (Vac_peak). The

  Here, FIG. 4 is a diagram schematically showing a functional unit of the controller (31) of FIG.

  FIG. 3 shows a case where the input-side detection cycle, which is the detection cycle of the input voltage detector (24), is longer than the cycle (power supply frequency) at which the input voltage (V1) takes the maximum value.

-Power factor improvement section-
As shown in FIG. 1, the power factor improvement part (25) is connected to the output of the rectification part (22) via the main power supply relay (23). The power factor improvement unit (25) is a boost type power factor improvement circuit, and performs a power factor improvement operation by boosting and smoothing the input voltage (V1).

  Specifically, the power factor improvement unit (25) in FIG. 1 includes a power factor improvement drive unit (30), a three-phase boost chopper circuit configured to be able to perform a three-phase interleaved operation, And two smoothing capacitors (26). Specifically, the power factor improvement unit (25) includes three reactors (L25a, L25b, L25c), three switching elements (Q25a, Q25b, Q25c), three resistors (R25a, R25b, R25c), and three diodes. (D25a, D25b, D25c) and one smoothing capacitor (26).

  One end of the reactor (L25a) is connected to the main power relay (23), and the input voltage (V1) is used as electric energy, and this is changed into magnetic flux energy and stored. The inductance value of the reactor (L25a) is appropriately determined according to the value of the current flowing on the power supply wiring (41), the switching frequency of the switching element (Q25a), and the like.

  The switching element (Q25a) is composed of an Nch insulated gate bipolar transistor, and is connected to the other end of the reactor (L25a). The switching element (Q25a) plays a role of switching between accumulation and discharge of energy based on the input voltage (V1) in the reactor (L25a). The switching element (Q25a) is controlled to be turned on and off by the power factor correction drive unit (30).

  The resistor (R25a) is a shunt resistor for detecting a power factor correction (PFC) current (Ipfc) flowing in the switching element (Q25a), and is a resistance between the switching element (Q25a) and the GND wiring (42). Connected between. The voltage (Vd1) of the resistor (R25a) is input to the controller (31) functioning as the PFC current calculation unit (31b) after AD conversion (see FIG. 4), and is used to calculate the PFC current (Ipfc). The PFC current (Ipfc) is used for drive control of the power factor improvement unit (25). This is because even if the output voltage (V2) fluctuates to some extent, stable energy is supplied to the subsequent stage of the power factor improvement unit (25). The resistance value of the resistor (R25a) is determined to be an appropriate value that does not hinder the voltage boosting operation by the power factor correction section (25).

  In FIG. 1, only the voltage (Vd1) of the resistor (R25c) is input to the controller (31), but the voltage (Vd1) of the resistors (R25a, R25b) is also input to the controller (31).

  The diode (D25a) is connected in series on the power supply wiring (41) on the output side of the reactor (L25a). In particular, the anode terminal of the diode (D25a) is connected downstream of the connection point between the reactor (L25a) and the switching element (Q25a) in the current flow direction. The diode (D25a) allows only a current flow from the reactor (L25a) side to the power conversion unit (28) side.

  The smoothing capacitor (26) is composed of, for example, an electrolytic capacitor, and one smoothing capacitor (26) is provided in common for the boost chopper circuit of each phase. The smoothing capacitor (26) is connected in parallel to each switching element (Q25a, Q25b, Q25c) on the output side of each reactor (L25a, L25b, L25c). The smoothing capacitor (26) charges and discharges energy released from each reactor (L25a, L25b, L25c), thereby generating a DC voltage with a relatively low ripple component.

  The power factor correction drive unit (30) is connected to the gate terminal of each switching element (Q25a, Q25b, Q25c) and the controller (31). The power factor correction drive unit (30) is configured by, for example, an integrated circuit. Based on the PFC drive command signal (Cpfc) from the controller (31), the power factor correction drive unit (30) controls the application of the gate voltage to each switching element (Q25a, Q25b, Q25c). Controls the power factor improving operation of the rate improving unit (25).

  Specifically, the power factor improvement drive unit (30) turns on and off each switching element (Q25a, Q25b, Q25c) in a short period when the power factor improvement unit (25) performs the power factor improvement operation. The gate control signals (G1, G2, G3) to be repeated in the above are output to the switching elements (Q25a, Q25b, Q25c). Conversely, the power factor improvement drive unit (30) keeps all the switching elements (Q25a, Q25b, Q25c) in the off state when the power factor improvement unit (25) does not perform the power factor improvement operation. Gate control signals (G1, G2, G3) are output to the switching elements (Q25a, Q25b, Q25c).

  The boosting operation (that is, the power factor improving operation) of the power factor improving unit (25) will be described taking a boosting chopper circuit for one phase as an example. First, when the switching element (Q25a) is turned on, a current path is formed from the power supply wiring (41) to the GND wiring (42) through the reactor (L25a), the switching element (Q25a), and the resistor (R25a), and the PFC current ( Ipfc) flows in this order. Then, the PFC current (Ipfc) flows through the reactor (L25a), so that energy is accumulated in the reactor (L25a). Next, when the switching element (Q25a) is turned off, the current path is cut off by the switching element (Q25a). The current corresponding to the energy accumulated in the reactor (L25a) flows into the smoothing capacitor (26) through the diode (D25a), and the voltage of the smoothing capacitor (26) increases.

  The other two-phase boost chopper circuits are connected in parallel with the above-described one-phase boost chopper circuit, and the operation is the same as described above.

  The number of components (reactors (L25a, L25b, L25c), etc.) of the power factor improvement unit (25) is an example, and is not limited to the above. Further, instead of the resistors (R25a, R25b, R25c), a current sensor (not shown) may detect the PFC current (Ipfc).

−Output voltage detector−
The output voltage detector (27) detects the output voltage (V2).

  As shown in FIGS. 1 and 4, the output voltage detection unit (27) mainly includes two resistors (27a, 27b) connected in series with each other, and a controller (31) that functions as an output voltage sampling unit (31c). It is constituted by. The two resistors (27a, 27b) connected in series with each other are connected to both ends of the smoothing capacitor (26) between the power factor improvement unit (25) and the power conversion unit (28). The voltage (V21) at the connection point between the resistors (27a, 27b) is input to the controller (31), sampled and AD-converted by the output voltage sampling unit (31c) at the output side detection period, and the output voltage (V2) Recognized as a detection result (Vdc).

  The output-side detection cycle may be shorter than the input-side detection cycle that is the detection cycle of the input voltage detector (24). As an example, when the input side detection period is about 1 sec, the output side detection period may be about 10 msec.

-Power converter-
The power conversion unit (28) is connected in parallel to the reactor (L25a, L25b, L25c) on the output side of the power factor improvement unit (25). When the output voltage (V2) is supplied from the power factor improvement unit (25), the power conversion unit (28) generates output AC power (SU, SV, SW).

  Although not shown, the power conversion unit (28) includes an inverter circuit and an inverter drive unit. The inverter circuit is configured to have a plurality of power elements each composed of, for example, an insulated gate bipolar transistor, and a plurality of freewheeling diodes connected in antiparallel to the power elements. The inverter drive part is comprised, for example by the integrated circuit, and is connected to the gate terminal of each power element. Based on the motor control signal (Pwm) output from the controller (31), the inverter drive unit turns on and off each power element by controlling the application of the gate voltage to each power element, and the inverter circuit Output AC power (SU, SV, SW) is generated.

-Current detector-
The current detection unit (29) detects the value of the input current (Im) to the power conversion unit (28). The input current (Im) flows from the commercial power supply (91) to the power supply wiring (41), the power conversion unit (28), and the motor (11), and again passes through the power conversion unit (28) and the GND wiring (42). The current that flows into the power factor correction section (25).

  As shown in FIGS. 1 and 4, the current detection unit (29) is mainly a controller that functions as a shunt resistor (29a) and an input current calculation unit (31d) connected in series on the GND wiring (42). 31) etc. The voltage (Vd2) of the shunt resistor (29a) is input to the controller (31), sampled and AD converted at a predetermined sampling period by the input current calculation unit (31d), and used to calculate the input current (Im). The

-Controller-
The controller (31) includes a memory and a CPU. As shown in FIG. 4, the controller (31), according to various programs stored in the memory, has the input voltage sampling unit (31a), the PFC current calculation unit (31b), the output voltage sampling unit (31c), In addition to the input current calculator (31d), it functions as a motor drive controller (31e) and a power factor correction controller (31f).

  A motor drive control part (31e) determines a motor control signal (Pwm) based on the rotor position information in a motor (11), and outputs this to the inverter drive part of a power converter (28). The rotor position information includes the detection result of the Hall element in the motor (11), the input current (Im) that is the detection result of the current detection unit (29), and the like. Further, the motor drive control unit (31e) uses the rotor position information and the detection results (Vac_peak, Vdc) of the respective detection units (24, 27) at times while the motor (11) is driven, Feedback control is performed for driving the motor (11).

  Further, the power factor improvement control unit (31f) performs control related to the power factor improvement unit (25). The control includes on / off control of the power factor improvement operation of the power factor improvement unit (25) during normal rotation of the motor (11), and the target of the output voltage (Vdc) that the power factor improvement unit (25) should output. Examples include variable control of the output target value (Vdc_ref), which is a value, and on / off control of the power factor improvement operation of the power factor improvement unit (25) accompanying the occurrence of an instantaneous voltage drop or an instantaneous power failure.

  On / off control of the power factor correction operation of the power factor improvement unit (25) during normal rotation of the motor (11) refers to the input current (Im), etc. when there is no instantaneous voltage drop or instantaneous power failure Based on the control of the power factor improvement operation. In the control, for example, when the input current (Im) exceeds the first threshold value, the power factor improvement unit (25) performs the power factor improvement operation, and the second threshold value where the input current (Im) is smaller than the first threshold value. If it falls below, the power factor improvement unit (25) does not perform the power factor improvement operation. In addition, in the said control, it replaces with the control method by input current (Im), the control method by the magnitude of the output power of a power factor improvement part (25), and a motor (11) is started, and a power factor improvement part (25) A control method that causes the power factor correction operation to be performed may be employed.

  Below, the control in a power converter device (20) when stopping the driving | operation of the apparatus driven by a power converter part (28) is explained in full detail.

<Control in power conversion device when stopping operation of driven device>
FIG. 5 is a graph showing an example of a signal waveform and the like in the power conversion device (20) of FIG. At time (T11), the controller (31) asserts the main power control signal (Cs) that controls the main power relay (23) and the motor control signal (Pwm) that controls the operation of the power converter (28). To do. Then, the main power supply relay (23) is turned on, the power converter (28) starts the switching operation, and the operation of the motor (11) is started. Thereafter, the input current (Im) to the power converter (28) increases and reaches a threshold value at time (T12). Then, the controller (31) asserts the PFC drive command signal (Cpfc), and the power factor improvement unit (25) starts the power factor improvement operation.

  Next, the controller (31) stops the operation of the motor (11) as a device driven by the power converter (28). At this time, the controller (31) instructs the power conversion unit (25) to stop the operation after instructing the power factor improvement unit (25) to stop the power factor improvement operation. Specifically, the controller (31) first negates the PFC drive command signal (Cpfc) at time (T13), and then the motor control signal (Pwm) at time (T14) after a predetermined delay time (TD) has elapsed. ). When the motor control signal (Pwm) is negated, the motor (11) stops.

  Thereafter, the power conversion device (20) repeats the same operation from time (T15) to time (T18). At time (T28), the controller (31) negates the main power control signal (Cs). Then, the main power supply relay (23) is turned off, and the entire operation of the power converter (20) is stopped. Note that the main power control signal (Cs) is negated because the controller (31) receives a motor stop command, or the motor is stopped urgently due to an overcurrent flowing through the power converter (28), etc. This is not because the operation and stop of the motor (11) are repeated.

  FIG. 6 is a graph showing an example of states of the power conversion unit (28) and the power factor improvement unit (25) when the control as shown in FIG. 5 is performed. At time (T31), the power factor improvement unit (25) starts to operate according to the PFC drive command signal (Cpfc). Then, the output voltage (V2) of the power factor improvement unit (25) reaches its target value (Vdc_ref) by the power factor improvement operation of the power factor improvement unit (25).

  Thereafter, the controller (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation. At time (T32), the power factor correction unit (25) stops operating. At this time, since the power converter (28) is operating, the output voltage (V2) starts to decrease. Thereafter, the controller (31) instructs the power conversion unit (28) to stop the operation, and the power conversion unit (28) stops the operation.

  Here, after the power factor improvement unit (25) stops operating, the power conversion unit (28) needs to stop operating. Also, after the controller (31) gives an instruction to the power factor correction unit (25) by the PFC drive command signal (Cpfc), until the switching element (Q25a, Q25b, Q25c) actually stops the switching operation, It takes a certain amount of time.

  Therefore, the delay time (TD) in FIG. 5 is at least switched by the switching elements (Q25a, Q25b, Q25c) after the controller (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation. This is the time until the operation stops. Specifically, the delay time (TD) is determined by the switching elements (Q25a, Q25b, Q25c) according to this signal after receiving the PFC drive command signal (Cpfc) negated by the power factor correction drive unit (30). Delay time until the gate control signal (G1, G2, G3) is output, and switching after the switching element (Q25a, Q25b, Q25c) receives the gate control signal (G1, G2, G3) This is the sum of the delay time until the operation is stopped.

  For comparison, an example in another case will be described. FIG. 7 is a graph showing an example of states of the power conversion unit (28) and the power factor improvement unit (25) when the delay time (TD) in FIG. 5 is zero. In other words, FIG. 7 is a graph in a case where instructions to stop the operation are simultaneously given to the power factor improvement unit (25) and the power conversion unit (28).

  At time (T41), the power factor improvement unit (25) starts to operate according to the PFC drive command signal (Cpfc). Then, the output voltage (V2) of the power factor improvement unit (25) reaches its target value (Vdc_ref) by the power factor improvement operation of the power factor improvement unit (25).

  Thereafter, the controller (31) simultaneously instructs the power factor improvement unit (25) and the power conversion unit (28) to stop the operation. Since the power factor improvement unit (25) has the power factor improvement drive unit (30), the time from when the signal for instructing to stop to when it actually stops is the power conversion unit (28) Longer. For this reason, at time (T42), first, the power conversion unit (28) stops its operation.

  At this time, the power factor improving unit (25) is still performing the power factor improving operation. However, because the load is gone, the power factor improvement unit (25) cannot follow the sudden change in load, and the output voltage (V2) of the power factor improvement unit (25) is more transient than its target value (Vdc_ref). Will rise. Thereafter, the power factor correction unit (25) stops operating, and the output voltage (V2) decreases. Since the output voltage (V2) of the power factor improvement unit (25) is higher than the target value (Vdc_ref), the switching elements (Q25a, Q25b, Q25c) and smoothing capacitors (26) of the power factor improvement unit (25) In addition, a higher voltage than usual is applied, and the possibility of failure of these elements due to overvoltage increases.

  In this embodiment, as shown in FIG. 5, the controller (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation, and then instructs the power conversion unit (28) to stop the operation. To do. Thereby, it is possible to avoid the output voltage (V2) from rising too much as shown in FIG. For this reason, it is possible to prevent the voltage applied to the switching elements (Q25a, Q25b, Q25c) and the smoothing capacitor (26) of the power factor improving section (25) from becoming too high.

  The case where the power conversion unit (28) stops operating after the power factor improving unit (25) stops operating by setting the delay time (TD) has been described. However, the controller (31) is not limited to this, and the controller (31) determines the power of the power factor improvement unit (25) based on the output voltage (V2) of the power factor improvement unit (25) (or a voltage obtained by dividing the output voltage (V21)). After detecting the stop of the rate improvement operation, the power conversion unit (28) may be instructed to stop the operation. Specifically, the controller (31) detects the power of the power factor improvement unit (25) when, for example, the power factor improvement unit (25) stops operating and the output voltage (V2) decreases by a predetermined voltage. The stop of the rate improvement operation may be detected.

  In an emergency, it is necessary to stop the motor (11) as soon as possible. Therefore, in an emergency, the controller (31) instructs the power conversion unit (28) to stop the operation before instructing the power factor improvement unit (25) to stop the power factor improvement operation. Also good. The case of emergency is, for example, when an overcurrent flows through the power converter (28) or when the discharge pressure of the compressor (72) as a device driven by the power converter (28) exceeds a threshold value It is. In an emergency, the main power relay (23) as a switch for controlling conduction between the rectifying unit (22) and the power factor improving unit (25) in FIG. 1 may be turned off. The power converter (20) replaces the main power supply relay (23) of FIG. 1 with the main power supply relay (23) as a switch for controlling conduction between the AC power supply (91) and the rectifying unit (22). You may have. The main power relay (23) may also be turned off in an emergency.

  The controller (31) measures the input current (Im) to the power converter (28) by the voltage (Vd2) of the shunt resistor (29a), so that an overcurrent has flowed through the power converter (28). Can be detected. When the controller (31) detects that an overcurrent has flowed into the power conversion unit (28), the controller (31) before instructing the power factor improvement unit (25) to stop the power factor improvement operation, the power conversion unit (28) May be instructed to stop the operation, or the main power relay (23) may be turned off.

  The power converter (20) may further include a current measuring unit that measures the input current (Im). When the current measurement unit detects that an overcurrent has flowed to the power conversion unit (28), the current measurement unit notifies the controller (31) of this by an interrupt, for example.

  The pressure sensor (79) is connected to piping on the discharge side of the compressor (72), and measures the discharge pressure of the compressor (72). The pressure sensor (79) turns off the main power supply relay (23) by a high voltage signal (Cp) when the discharge pressure exceeds the threshold value. The main power supply relay (23) notifies the controller (31), for example, by interruption that the discharge pressure has exceeded the threshold value. Upon receiving the notification, the controller (31) may instruct the power conversion unit (28) to stop the operation before instructing the power factor improvement unit (25) to stop the power factor improvement operation.

<Effect of embodiment>
As described above, since the power factor improvement unit (25) is instructed to stop the power factor improvement operation and then the power conversion unit (28) is instructed to stop the operation, the power factor improvement unit (25) An increase in output voltage can be suppressed. Since the voltage applied to the switching elements (Q25a, Q25b, Q25c) of the power factor improvement unit (25) and the smoothing capacitor (26) can be suppressed, these elements fail while suppressing the pressure resistance of these elements. The possibility can be suppressed.

  As described above, the present invention is useful for a power conversion device having a boost type power factor correction unit, an air conditioner having the same, and the like.

20 Power converter
22 Rectifier
23 Main power relay (switch)
25 Power factor improvement department
28 Power converter
31 Controller (Controller)
70 Air conditioner
72 Compressor
L25a, L25b, L25c reactor
Q25a, Q25b, Q25c Switching element
V1 input voltage
V2 output voltage

Claims (7)

A rectifying unit (22) for rectifying the input AC from the AC power source (91);
A power factor correction unit (25) that performs power factor correction operation on the input voltage (V1) output from the rectification unit (22);
A power conversion unit (28) connected to the output of the power factor improvement unit (25) to generate output AC power;
A control unit (31) for controlling the power factor improvement operation of the power factor improvement unit (25),
When stopping the operation of the device driven by the power conversion unit (28), the control unit (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation, and then An electric power converter characterized by instructing the converter (28) to stop the operation. In claim 1,
The control unit (31) instructs the power conversion unit (28) to stop the operation after a lapse of a predetermined time after instructing the power factor improvement unit (25) to stop the power factor improvement operation. A power conversion device. In claim 2,
The power factor improvement section (25)
Reactors (L25a, L25b, L25c),
A switching element (Q25a, Q25b, Q25c) connected in series to the reactor (L25a, L25b, L25c),
The switching element (Q25a, Q25b, Q25c) stops the switching operation at least after the control unit (31) instructs the power factor improvement unit (25) to stop the power factor improvement operation for the predetermined time. A power converter characterized by the time until In claim 1,
The control unit (31) detects the stop of the power factor improvement operation of the power factor improvement unit (25) due to a decrease in the output voltage of the power factor improvement unit (25), and then causes the power conversion unit (28) to An electric power converter characterized by giving an instruction to stop the operation. In claim 1,
The controller (31) has a discharge pressure of a compressor (72) as a device driven by the power converter (28) when an overcurrent flows through the power converter (28) or exceeds a threshold value. The power conversion unit (25) is instructed to stop the operation before the power factor improvement unit (25) is instructed to stop the power factor improvement operation. . In claim 1,
A switch (23) for controlling conduction between the rectifying unit (22) and the power factor improving unit (25) or between the AC power source (91) and the rectifying unit (22);
When an overcurrent flows through the power converter (28), or when the discharge pressure of the compressor (72) as a device driven by the power converter (28) exceeds a threshold value, the switch ( 23) A power converter characterized by being turned off. An air conditioner comprising the power converter according to any one of claims 1 to 6.

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