JP6937936B2 - DC power supply, motor drive, blower, compressor and air conditioner - Google Patents

Description

The present invention relates to a DC power supply device that converts AC power supplied from an AC power supply into DC power and supplies it to a load, a motor drive device provided with the DC power supply device, a blower and a compressor provided with the motor drive device, and the like. In addition, the present invention relates to the blower or an air conditioner equipped with the compressor.

In the DC power supply device, one of the problems is to suppress the loss on the circuit through which the current flows to improve the efficiency. As a DC power supply device for the purpose of improving efficiency, in the DC power supply device described in Patent Document 1 below, two of the four diodes are replaced with MOSFETs (Metal-Oxide-Semiconductor Field-Effective Transistor). A rectifier having a different configuration is disclosed. In the rectifier, two diodes and two MOSFETs are bridge-connected to form a bridge circuit.

In the DC power supply device of Patent Document 1, the conduction loss is reduced by controlling the MOSFET in synchronization with the timing when the current starts to flow in the bridge circuit and the timing when the current flowing in the bridge circuit changes to zero. This technique is called synchronous rectification.

Japanese Unexamined Patent Publication No. 2012-143154

In order to effectively perform synchronous rectification, it is necessary to accurately grasp the timing when the current starts to flow in the bridge circuit. On the other hand, the current flowing through the bridge circuit is detected by the current detector, but there is a detection error in the detected value of the current detector. An example of the detection error is an offset component superimposed on the detected value. When synchronous rectification is performed using the detected value in which the offset component is superimposed, the synchronous rectification is performed at a point different from the timing when the current actually starts to flow, so that a loss occurs. Therefore, there is room for improvement in improving efficiency.

The present invention has been made in view of the above, and an object of the present invention is to obtain a DC power supply device capable of reducing a loss due to a detection error of a current detector and further improving efficiency. ..

In order to solve the above-mentioned problems and achieve the object, the DC power supply device according to the present invention includes a reactor whose one end is connected to an AC power supply and a reactor which is connected to the other end of the reactor and includes at least one switching element. It includes a bridge circuit that converts the first AC voltage output from the AC voltage into a DC voltage, and a capacitor that smoothes the second voltage, which is the voltage on the DC side of the bridge circuit. Further, the DC power supply device includes a first voltage detector for detecting the first voltage and a first current detector for detecting the first current of the alternating current flowing between the alternating current power supply and the bridge circuit. Further, the DC power supply device calculates the detection error included in the detection value of the first current, generates a correction value of the detection value of the first current based on the detection error, and detects the detection value of the first voltage and the first current. It is provided with a control unit that controls the switching element of the bridge circuit based on the correction value of the detected value of.

According to the motor drive device according to the present invention, it is possible to reduce the loss caused by the detection error of the current detector and further improve the efficiency.

A circuit diagram showing the configuration of the DC power supply device according to the first embodiment. The figure which provides the description of the operation mode of the DC power supply device which concerns on Embodiment 1. The figure which shows one of the current paths in the passive synchronous rectification mode in the bridge circuit of Embodiment 1. The figure which shows typically the current-loss characteristic in a general switching element. The figure which shows one of the current paths in the simple switching mode in the bridge circuit of Embodiment 1. The figure which shows the switch state of each switching element in the passive synchronous rectification mode in the bridge circuit of Embodiment 1. The figure provided for the description of the reverse current which may occur in the bridge circuit of Embodiment 1. The block diagram which shows the structure of the main part of the control part in Embodiment 1. The figure provided for the explanation of the operation of the detection value correction part shown in FIG. A block diagram showing a configuration of a modified example of the detection value correction unit shown in FIG. A block diagram showing an example of a hardware configuration that embodies the function of the control unit according to the first embodiment. A block diagram showing another example of a hardware configuration that embodies the function of the control unit according to the first embodiment. The figure which shows the application example to the motor drive device which concerns on Embodiment 2. The figure which shows the example which applied the motor drive device shown in FIG. 13 to an air conditioner.

The DC power supply device, the motor drive device, the blower, the compressor, and the air conditioner according to the embodiment of the present invention will be described below with reference to the accompanying drawings. The present invention is not limited to the embodiments shown below. Further, in the following, the electrical connection will be described simply as "connection".

Embodiment 1.
FIG. 1 is a circuit diagram showing a configuration of a DC power supply device 100 according to a first embodiment. The DC power supply device 100 according to the first embodiment is a power supply device that converts the AC power supplied from the single-phase AC power supply 1 into DC power and supplies it to the load 500. As shown in FIG. 1, the DC power supply device 100 according to the first embodiment includes a reactor 2, a bridge circuit 3, a capacitor 4, a control unit 8, and a gate drive circuit 15 which is a drive circuit. Further, the DC power supply device 100 includes a voltage detector 5 which is a first voltage detector, a current detector 6 which is a first current detector, a voltage detector 7 which is a second voltage detector, and the like. To be equipped.

In FIG. 1, an example of a load 500 is a motor built into a blower, compressor or air conditioner. A breaker 10 which is a circuit breaker for wiring for protecting the DC power supply device 100 is provided between the AC power supply 1 and the DC power supply device 100.

One end of the reactor 2 is connected to the AC power supply 1 via the breaker 10, and the other end of the reactor 2 is connected to the bridge circuit 3. The bridge circuit 3 converts the AC voltage output from the AC power supply 1 into a DC voltage.

The bridge circuit 3 includes a first leg 31 and a second leg 32. The first leg 31 and the second leg 32 are connected in parallel. In the first leg 31, the first upper arm element 311 and the first lower arm element 312 are connected in series. In the second leg 32, the second upper arm element 321 and the second lower arm element 322 are connected in series. The other end of the reactor 2 is connected to a connection point 3a between the first upper arm element 311 and the first lower arm element 312 in the first leg 31. The connection point 3b between the second upper arm element 321 and the second lower arm element 322 is connected to the other end of the AC power supply 1. In the bridge circuit 3, the connection points 3a and 3b form an AC terminal.

In FIG. 1, the reactor 2 is connected between one end of the AC power supply 1 and the connection point 3a, but even if it is connected between the other end of the AC power supply 1 and the connection point 3b. good.

In the bridge circuit 3, the side where the connection points 3a and 3b are located is called the "AC side". Further, the AC voltage output from the AC power supply 1 is called a "power supply voltage", and the cycle of the power supply voltage is called a "power supply cycle". The power supply voltage may be referred to as a "first voltage".

The first upper arm element 311 includes a switching element Q1 and a diode D1 connected in antiparallel to the switching element Q1. The first lower arm element 312 includes a switching element Q2 and a diode D2 connected in antiparallel to the switching element Q2. The second upper arm element 321 includes a switching element Q3 and a diode D3 connected in antiparallel to the switching element Q3. The second lower arm element 322 includes a switching element Q4 and a diode D4 connected in antiparallel to the switching element Q4.

In FIG. 1, metal oxide semiconductor field effect transistors (Metal Oxide Semiconductor Field Effect Transistors: MOSFETs) are illustrated for each of the switching elements Q1, Q2, Q3, and Q4, but are not limited to MOSFETs. A MOSFET is a switching element capable of passing a current in both directions between a drain and a source. Any switching element may be used as long as it is a switching element capable of bidirectionally flowing a current between the first terminal corresponding to the drain and the second terminal corresponding to the source, that is, a bidirectional switching element.

Further, antiparallel means that the first terminal corresponding to the drain of the MOSFET and the cathode of the diode are connected, and the second terminal corresponding to the source of the MOSFET and the anode of the diode are connected. As the diode, a parasitic diode that the MOSFET itself has inside may be used. Parasitic diodes are also called body diodes.

Further, at least one of the switching elements Q1, Q2, Q3, and Q4 is not limited to a MOSFET formed of a silicon-based material, but is formed of a wide bandgap semiconductor such as silicon carbide, gallium nitride, gallium oxide, or diamond. It may be a MOSFET.

In general, wide bandgap semiconductors have higher withstand voltage resistance and heat resistance than silicon semiconductors. Therefore, by using a wide bandgap semiconductor for at least one of the switching elements Q1, Q2, Q3, and Q4, the withstand voltage resistance and the allowable current density of the switching element are increased, and the semiconductor module incorporating the switching element can be miniaturized. Can be converted.

One end of the capacitor 4 is connected to the DC bus 16a on the high potential side. The DC bus 16a is drawn from the connection point 3c between the first upper arm element 311 in the first leg 31 and the second upper arm element 321 in the second leg 32. The other end of the capacitor 4 is connected to the DC bus 16b on the low potential side. The DC bus 16b is drawn from the connection point 3d between the first lower arm element 312 in the first leg 31 and the second lower arm element 322 in the second leg 32. In the bridge circuit 3, the connection points 3c and 3d form a DC terminal. Further, in the bridge circuit 3, the side where the connection points 3c and 3d are located is referred to as a "DC side".

The output voltage of the bridge circuit 3 is applied to both ends of the capacitor 4. The capacitor 4 smoothes the output voltage of the bridge circuit 3. The capacitor 4 is connected to the DC bus lines 16a and 16b. The voltage smoothed by the capacitor 4 is called "bus voltage". The bus voltage may be referred to as a "second voltage". The bus voltage is also the voltage applied to the load 500.

The voltage detector 5 detects the power supply voltage and outputs the detected value Vs of the power supply voltage to the control unit 8. The power supply voltage is an absolute value of the instantaneous voltage of the AC power supply 1. The effective value of the instantaneous voltage may be used as the power supply voltage.

The current detector 6 detects the alternating current flowing between the alternating current power supply 1 and the bridge circuit 3, and outputs the detected value Is of the alternating current to the control unit 8. An example of the current detector 6 is a current transformer (CT). The AC current flowing between the AC power supply 1 and the bridge circuit 3 is appropriately referred to as a "power supply current". Further, the power supply current may be referred to as a "first current".

The voltage detector 7 detects the bus voltage and outputs the detected value Vdc of the bus voltage to the control unit 8.

The control unit 8 controls each switching element constituting the bridge circuit 3 based on the detection value Vs of the voltage detector 5, the detection value Is of the current detector 6, and the detection value Vdc of the voltage detector 7. The control signals S311, S3212, S321 and S322 are generated. The control signal S311 is a control signal for controlling the switching element Q1. Similarly, the control signal S312 is a control signal for controlling the switching element Q2, the control signal S321 is a control signal for controlling the switching element Q3, and the control signal S322 controls the switching element Q4. It is a control signal to do. The control signals S311, S3212, S321, and S322 generated by the control unit 8 are input to the input port 15a of the gate drive circuit 15.

The gate drive circuit 15 generates drive pulses G311 and G312 and G321 and G322 for driving each switching element constituting the bridge circuit 3 based on the control signals S311 and S312 and S321 and S322. The drive pulse G311 is a drive pulse for driving the switching element Q1. Similarly, the drive pulse G312 is a drive pulse for driving the switching element Q2, the drive pulse G321 is a drive pulse for driving the switching element Q3, and the drive pulse G322 drives the switching element Q4. It is a drive pulse to do.

Next, the operation of the main part of the DC power supply device 100 according to the first embodiment will be described with reference to the drawings of FIGS. 1 to 6.

FIG. 2 is a diagram provided for explaining an operation mode of the DC power supply device 100 according to the first embodiment. FIG. 2 shows three operation modes: a passive synchronous rectification mode, a simple switching mode, and a pulse width modulation (PWM) control mode. FIG. 3 is a diagram showing one of the current paths in the passive synchronous rectification mode in the bridge circuit 3 of the first embodiment. FIG. 4 is a diagram schematically showing a current-loss characteristic in a general switching element. FIG. 5 is a diagram showing one of the current paths in the simple switching mode in the bridge circuit 3 of the first embodiment. FIG. 6 is a diagram showing a switch state of each switching element in the passive synchronous rectification mode in the bridge circuit 3 of the first embodiment.

The upper part of FIG. 2 shows the power supply voltage and the power supply current in the passive synchronous rectification mode. This operation mode is a mode in which synchronous rectification is performed without boosting. Non-boosting means that the bus voltage is not boosted, and that the power supply short-circuit operation is not performed in the operation. The power short-circuit operation will be described later. Further, synchronous rectification is a control method in which a switching element connected in antiparallel to a diode is turned on at the timing when a current flows through the diode.

FIG. 3 shows a charging path for the capacitor 4 when the power supply voltage is positive and synchronous rectification is performed. As shown in FIG. 3, it is assumed that the polarity of the power supply voltage is positive when the upper terminal of the AC power supply 1 has a positive potential. Further, it is assumed that the polarity of the power supply voltage is negative when the upper terminal of the AC power supply 1 has a negative potential.

In FIG. 3, when the capacitor 4 is charged by the current supplied from the AC power supply 1, when the switching elements Q1 and Q4 are not turned on, the AC power supply 1, the reactor 2, the diode D1, the capacitor 4, the diode D4, and the AC power supply are used. Current flows in the order of 1. The diode does not conduct unless a voltage corresponding to the voltage drop is applied in the direction in which the current flows, that is, in the forward direction. Therefore, as shown in the upper part of FIG. 2, in the period of the half cycle T1 in which the power supply voltage is positive, the current flows in the period T2 shorter than the half cycle T1. In the passive synchronous rectification mode, the switching elements Q1 and Q4 are controlled to be ON in the period T2 according to the conduction timing of the diodes D1 and D4. Therefore, in the period T2, the current flows in the order of the AC power supply 1, the reactor 2, the switching element Q1, the capacitor 4, the switching element Q4, and the AC power supply 1.

The same operation is performed in the half cycle when the power supply voltage is negative. However, in the period T3 in the half cycle in which the power supply voltage is negative, the switching elements Q2 and Q3 are controlled to be ON according to the conduction timing of the diodes D2 and D3.

FIG. 4 shows the loss characteristic of the diode and the loss characteristic when the switching element is turned on. As shown in FIG. 4, in the region A where the current is smaller than the current value I0, the loss of the diode is larger than the loss of the switching element. By utilizing this characteristic and using synchronous rectification that turns on the switching element connected to the diode in antiparallel to the timing when the current flows through the diode, the device can be operated with high efficiency.

Further, in the middle part of FIG. 2, the power supply voltage and the power supply current in the simple switching mode are shown. This operation mode is an operation mode in which the power supply short-circuit operation is performed one or several times in a half-cycle period of the power supply voltage. In the example of the middle part of FIG. 2, the power supply short-circuit operation is performed once in the half-cycle period of the power supply voltage.

FIG. 5 shows a short-circuit path of the AC power supply 1 via the reactor 2 when the power supply voltage is positive and synchronous rectification is performed. As shown in FIG. 5, the switching elements Q1 and Q3 are turned on during the period T4. In this way, the current flows in the order of the AC power supply 1, the reactor 2, the switching element Q1, the switching element Q3, and the AC power supply 1, and the electric energy is stored in the reactor 2.

After the period T4, the operation is performed in the passive synchronous rectification mode shown in the upper part of FIG. Immediately after the period T4, the sum of the voltage of the AC power supply 1 and the voltage generated in the reactor 2 is applied to the bridge circuit 3. Therefore, the diodes D1 and D4 of the bridge circuit 3 are conductive. Then, the switching elements Q1 and Q4 are turned on in accordance with the conduction timing of the diodes D1 and D4, and the power supply current flows.

In FIG. 5, the switching elements Q1 and Q3 are turned on, but instead of this, the switching elements Q2 and Q4 may be turned on. In this case, the current flows in the order of the AC power supply 1, the reactor 2, the switching element Q2, the switching element Q4, and the AC power supply 1.

The same applies to the negative half cycle, and after one or several power supply short-circuit operations, a passive synchronous rectification operation is performed. In the power supply short-circuit operation, the switching elements Q1 and Q3 may be turned on, or the switching elements Q2 and Q4 may be turned on.

Further, the lower part of FIG. 2 shows the power supply voltage and the power supply current in the PWM control mode. In this operation mode, the power supply short-circuit operation in which the electric energy is stored in the reactor 2 and the charging operation in which the capacitor 4 is charged by using the electric energy stored in the reactor 2 are alternately repeated. Switching between the power short-circuit operation and the charging operation is performed at a high frequency of several kHz to several tens of kHz. As a result, as shown in the lower part of FIG. 2, the power supply current is controlled to a sinusoidal current.

FIG. 6 shows the states of the switching elements Q1 to Q4 when the bridge circuit 3 is operated in the passive synchronous rectification mode, together with the waveforms of the power supply voltage and the power supply current. In the example of FIG. 6, in the passive synchronous rectification mode, the operating state when the switching elements Q3 and Q4 are alternately ON-controlled and OFF-controlled in the cycle of the power supply voltage, and the switching elements Q1 and Q2 are ON-controlled for synchronous rectification. It is shown. As shown in the figure, the switching elements Q1 and Q2 are switching elements that operate in synchronization with the power supply current, whereas the switching elements Q3 and Q4 are switching elements that operate in synchronization with the power supply voltage. In FIG. 6, the period other than that described as ON is the OFF state. In the example of FIG. 6, the switching elements Q1 and Q2 are shown as switching elements synchronized with the power supply current, and the switching elements Q3 and Q4 are shown as switching elements synchronized with the power supply voltage. good. That is, the switching elements Q1 and Q2 may be used as switching elements synchronized with the power supply voltage, and the switching elements Q3 and Q4 may be used as switching elements synchronized with the power supply current.

The above-mentioned three modes can be switched according to the load conditions. This makes it possible to operate the DC power supply device 100 with high efficiency.

Note that FIG. 1 shows a configuration in which four bidirectional switching elements, which are MOSFETs, are bridge-connected, but the present invention is not limited to this. For example, a bridge circuit may be formed by using one bidirectional switching element and three diodes. That is, at least one of the four elements constituting the bridge circuit may be a bidirectional switching element. If at least one is a bidirectional switching element, the bus voltage can be boosted by the simple switching mode.

Next, the phenomenon of reverse current, which is a problem in the bridge circuit 3 of the first embodiment, will be described with reference to FIG. 7. FIG. 7 is a diagram for explaining the reverse current that can occur in the bridge circuit 3 of the first embodiment. In FIG. 7, the waveform of the K1 portion shown by the rectangular frame of the broken line in FIG. 6 is shown enlarged in the time axis direction. In the following, a case where the offset component is superimposed on the detected value Is of the current detector 6 will be described as an example.

In FIG. 7, the waveform of the power supply voltage is shown in the upper part, and the waveform of the power supply current is shown in the middle upper part. Further, the control signals S311 and S312 for controlling the switching elements Q1 and Q2 are shown in the middle and lower stages, and the control signals S321 and S322 for controlling the switching elements Q3 and Q4 are shown in the lower middle stage.

As shown in FIG. 6, the switching element Q1 is normally turned on when a positive power supply current flows. Originally, it should be turned off at the timing indicated by the broken line in the lower middle part of FIG. However, since the detected value Is of the current detector 6 contains an offset component, the control signal S311 is not turned off at the zero crossing point t1 of the power supply current in which the positive power supply current changes to the negative power supply current, and the control signal S311 is delayed. It is OFF. Therefore, as shown in the middle upper part of FIG. 7, a phenomenon occurs in which the negative current returns to the zero point of the power supply current. This phenomenon is reverse current.

FIG. 8 is a block diagram showing a configuration of a main part of the control unit 8 according to the first embodiment. The control unit 8 includes a detection value correction unit 80 shown in FIG. The reverse current described above causes a conduction loss, which reduces the efficiency of the DC power supply device 100. Therefore, in the first embodiment, the detection value correction unit 80 shown in FIG. 8 is configured in the control unit 8.

The detection value correction unit 80 calculates the detection error included in the detection value Is of the power supply current, corrects the detection value Is of the power supply current based on the detection error, and generates the correction value Is1 of the corrected detection value Is. .. The control unit 8 controls each switching element of the bridge circuit 3 by using the correction value Is1 of the detected value Is to suppress a reverse current that may occur in the bridge circuit 3.

Next, the internal operation of the detection value correction unit 80 in the first embodiment will be described with reference to the drawings of FIGS. 8 and 9. FIG. 9 is a diagram for explaining the operation of the detection value correction unit 80 shown in FIG.

As shown in FIG. 8, the detection value correction unit 80 includes a correction value calculation unit 81 which is a calculation unit, an output determination unit 82 which is a determination unit, and a correction value output unit 83 which is an output unit. The detection value Vs of the power supply voltage and the detection value Is of the power supply current are input to the detection value correction unit 80.

In FIG. 9, the waveform of the detected value Is of the power supply current is shown in the upper part. The determination value by the output determination unit 82 is shown in the middle upper portion. The waveform of the offset amount Ifs calculated by the correction value calculation unit 81 is shown in the middle and lower stages. In the lower part, the waveform of the correction value Is1 of the detection value Is of the power supply current output from the correction value output unit 83 is shown.

The correction value calculation unit 81 calculates an offset amount Ifs, which is an offset component included in the detected value Is of the power supply current, as a detection error based on the detected value Vs of the power supply voltage and the detected value Is of the power supply current.

As shown in FIG. 9, the offset amount Ifs can be calculated by capturing the timing of the zero cross of the power supply voltage, sampling the current for one cycle from the zero cross, and integrating or averaging the sampling values. can. Although FIG. 9 shows an example of sampling the current for one cycle, sampling for a plurality of cycles may be performed. By sampling the currents for a plurality of cycles, the calculation accuracy of the offset amount Ifs can be improved.

The output determination unit 82 determines whether or not the calculation process by the correction value calculation unit 81 is being carried out, that is, whether or not the offset amount Ifs is being calculated.

8 and 9 show specific examples. As shown in the middle upper section of FIG. 9, the output determination unit 82 generates a determination value inside the output determination unit 82. Specifically, the output determination unit 82 generates a determination value “0” if the correction value calculation unit 81 is in the process of calculating the offset amount Ifs, and the determination value “1” if the correction value calculation unit 81 is not in the process of calculating the offset amount Ifs. To generate. The period in which the determination value is “0” is a section in which the output of the offset amount Ifs is prohibited. Further, the period in which the determination value is "1" is a section in which the output of the offset amount Ifs is permitted. As shown in FIG. 8, the output Ia of the output determination unit 82 can be generated by the formula Ia = determination value × Ifs. That is, if the determination value is "0", Ia = 0, and if the determination value is "1", Ia = Ifs.

Therefore, if the calculation process by the correction value calculation unit 81 is being executed, the output determination unit 82 outputs a zero-level signal to the correction value output unit 83, and the calculation process by the correction value calculation unit 81 is not being executed. For example, the offset amount Ifs is output to the correction value output unit 83.

The correction value output unit 83 outputs the correction value Is1 of the detection value Is of the power supply current when the calculation process by the correction value calculation unit 81 is not being executed.

8 and 9 show specific examples. In FIG. 8, the function of the correction value output unit 83 is realized by the subtractor 83a. In the subtractor 83a, the output Ia of the output determination unit 82 is subtracted from the detected value Is of the power supply current. The output waveform of the correction value output unit 83 is shown in the lower part of FIG. In the lower part of FIG. 9, the correction value Is1 of the detection value Is in which the offset amount Ifs is corrected and the detection error is suppressed during the output permission period by the correction value output unit 83 is shown.

The subtractor 83a shown in FIG. 8 may be composed of an adder. If the offset amount output by the output determination unit 82 in FIG. 8 is not the one shown in the middle and lower parts of FIG. 9 but the correction amount due to the offset with the inverted sign is output, the power supply current detection value Is. By adding the output Ia of the output determination unit 82 and the output Ia of the output determination unit 82, the intended value can be output.

The detection value correction unit 80 shown in FIG. 8 can be replaced by the detection value correction unit 80a shown in FIG. FIG. 10 is a block diagram showing a configuration of a modified example of the detection value correction unit 80 shown in FIG.

In FIG. 10, the detection value correction unit 80a is composed of a high-pass filter. That is, the detection value correction unit 80a is a processing unit that uses the detection value Is of the power supply current as an input signal and outputs the signal filtered by the high-pass filter as the correction value Is1 of the detection value Is of the power supply current.

The characteristics of the high-pass filter in the detection value correction unit 80a are represented by the equations in the figure. The input x (t) represents the change in the detected value Is of the power supply current as a time-series function. Further, the output y (t) represents the change of the correction value Is1 of the detected value Is as a time-series function. Further, x (t-1) is an input value at the previous processing time, and y (t-1) is an output value at the previous processing time. Further, fc is the cutoff frequency of the filter, and Ts is a time constant that determines the rising and falling characteristics of the filter. Even if a high-pass filter having such characteristics is used, it is possible to reduce the offset component included in the detected value Is of the power supply current.

As described above, according to the DC power supply device according to the first embodiment, the detection value correction unit provided in the control unit calculates the detection error included in the detection value of the power supply current, and uses the calculated detection error as the calculated detection error. Based on this, the detected value of the power supply current is corrected, and the corrected value of the detected value of the power supply current is generated. Then, the control unit controls the switching element of the bridge circuit based on the corrected value of the detected value of the power supply voltage and the detected value of the power supply current. These controls suppress the reverse current that can occur in the bridge circuit. As a result, the loss caused by the detection error of the current detector can be reduced, and the efficiency can be further improved.

Next, the hardware configuration for realizing the function of the detection value correction unit 80 in the first embodiment will be described with reference to the drawings of FIGS. 11 and 12. FIG. 11 is a block diagram showing an example of a hardware configuration that embodies the function of the detection value correction unit 80 according to the first embodiment. FIG. 12 is a block diagram showing another example of the hardware configuration that embodies the function of the detection value correction unit 80 in the first embodiment.

When the function of the detection value correction unit 80 according to the first embodiment is realized, as shown in FIG. 11, the processor 300 that performs the calculation, the memory 302 that stores the program read by the processor 300, and the input / output of the signal. It can be configured to include an interface 304 that outputs.

The processor 300 may be a computing means such as an arithmetic unit, a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). Further, the memory 302 includes a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Program ROM), or an EEPROM (registered trademark) (Electrically EPROM). Examples thereof include magnetic disks, flexible disks, optical disks, compact disks, mini disks, and DVDs (Digital Versaille Discs).

The memory 302 stores a program that executes the function of the detection value correction unit 80 according to the first embodiment. The processor 300 sends and receives necessary information via the interface 304, the processor 300 executes a program stored in the memory 302, and the processor 300 refers to a table stored in the memory 302 to perform the above-described processing. It can be carried out. The calculation result by the processor 300 can be stored in the memory 302.

Further, the processor 300 and the memory 302 shown in FIG. 11 may be replaced with the processing circuit 305 as shown in FIG. The processing circuit 305 corresponds to a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. The information input to the processing circuit 305 and the information output from the processing circuit 305 can be performed via the interface 304.

Embodiment 2.
FIG. 13 is a diagram showing an example of application to the motor drive device 101 according to the second embodiment. The DC power supply device 100 described in the first embodiment can be applied to a motor drive device that supplies DC power to an inverter. Hereinafter, an example of application of the DC power supply device 100 described in the first embodiment to the motor drive device will be described.

The motor drive device 101 according to the second embodiment shown in FIG. 13 has a DC power supply device 100 according to the first embodiment and an inverter 500a. As described above, the DC power supply device 100 is a device that converts AC power into DC power. The inverter 500a is a device that converts DC power output from the DC power supply device 100 into AC power.

A motor 500b is connected to the output side of the inverter 500a. The inverter 500a drives the motor 500b by supplying the converted AC power to the motor 500b.

The motor drive device 101 shown in FIG. 13 can be applied to products such as a blower, a compressor, and an air conditioner.

FIG. 14 is a diagram showing an example in which the motor drive device 101 shown in FIG. 13 is applied to an air conditioner. A motor 500b is connected to the output side of the motor drive device 101, and the motor 500b is connected to the compression element 504. The compressor 505 includes a motor 500b and a compression element 504. The refrigeration cycle unit 506 is configured to include a four-way valve 506a, an indoor heat exchanger 506b, an expansion valve 506c, and an outdoor heat exchanger 506d.

The flow path of the refrigerant circulating inside the air conditioner is from the compression element 504 via the four-way valve 506a, the indoor heat exchanger 506b, the expansion valve 506c, the outdoor heat exchanger 506d, and again via the four-way valve 506a. , It is configured to return to the compression element 504. The motor drive device 101 receives AC power from the AC power supply 1 and rotates the motor 500b. The compression element 504 executes a compression operation of the refrigerant by rotating the motor 500b, and the refrigerant can be circulated inside the refrigeration cycle unit 506.

According to the motor drive device according to the second embodiment, the DC power supply device according to the first embodiment is provided. As a result, the effects described in the first embodiment can be enjoyed in the products such as the blower, the compressor and the air conditioner to which the motor drive device according to the second embodiment is applied.

Further, the configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is configured without departing from the gist of the present invention. It is also possible to omit or change a part of.

1 AC power supply, 2 reactors, 3 bridge circuits, 3a, 3b, 3c, 3d connection points, 4 capacitors, 5, 7 voltage detectors, 6 current detectors, 8 controls, 10 breakers, 15 gate drive circuits, 15a inputs Port, 16a, 16b DC bus, 31 1st leg, 32 2nd leg, 80, 80a detection value correction unit, 81 correction value calculation unit, 82 output judgment unit, 83 correction value output unit, 83a subtractor, 100 DC power supply, 101 motor drive, 300 processor, 302 memory, 304 interface, 305 processing circuit, 311 first upper arm element, 312 first lower arm element, 321 second upper arm element, 322 second Lower arm element, 500 load, 500a inverter, 500b motor, 504 compression element, 505 compressor, 506 refrigeration cycle section, 506a four-way valve, 506b indoor heat exchanger, 506c expansion valve, 506d outdoor heat exchanger, D1, D2 D3, D4 diode, Q1, Q2, Q3, Q4 switching element.

Claims (9)

A reactor with one end connected to an AC power supply,
A bridge circuit that is connected to the other end of the reactor, includes at least one switching element, and converts an AC first voltage output from the AC power supply into a DC voltage.
A capacitor that smoothes the second voltage, which is the voltage on the DC side of the bridge circuit,
The first voltage detector that detects the first voltage and
A first current detector that detects the first AC current flowing between the AC power supply and the bridge circuit, and
The detection error included in the detection value of the first current is calculated, the correction value of the detection value of the first current is generated based on the detection error, and the detection value of the first voltage and the detection of the first current are detected. A control unit that controls the switching element of the bridge circuit based on the correction value of the value is provided .
The control unit
A calculation unit that calculates an offset component included in the detection value of the first current as the detection error based on the detection value of the first voltage and the detection value of the first current.
A determination unit that determines whether or not the calculation process by the calculation unit is being executed,
When the determination unit determines that the calculation process is being performed, the detection value of the first current is output, and when the determination unit determines that the calculation process is not being executed, the detection value is output. , A DC power supply device including an output unit that outputs a correction value of a detected value of the first current. The determination unit outputs a zero-level signal to the output unit if the calculation process by the calculation unit is being executed, and outputs an offset component to the output unit if the calculation process by the calculation unit is not being executed. Output
The DC power supply device according to claim 1. The DC power supply device according to claim 1 or 2 , wherein the bridge circuit has a configuration in which at least one of the diodes constituting the circuit is replaced with a bidirectional switching element. The DC power supply device according to claim 3 , wherein at least one of the switching elements constituting the bridge circuit is formed of a wide bandgap semiconductor. The DC power supply device according to claim 4 , wherein the wide bandgap semiconductor is silicon carbide, gallium nitride, gallium oxide, or diamond. The DC power supply device according to any one of claims 1 to 5.
A motor drive device including an inverter that converts DC power output from the DC power supply device into AC power. A blower including the motor driving device according to claim 6. A compressor including the motor driving device according to claim 6. An air conditioner including at least one of the blower according to claim 7 and the compressor according to claim 8.

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