JP3806678B2 - Power supply device and motor control device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply device that converts alternating current power into direct current power, and more particularly to a power supply device that improves power factor by controlling a power supply current waveform in a sine wave shape by a short circuit operation once or a plurality of times in a half cycle of an alternating current power supply.
[0002]
[Prior art]
Japanese Laid-Open Patent Publication No. 2002-101550 discloses a power supply device that performs a short circuit operation once in a half cycle of an AC power supply to control an input current waveform in a sine wave shape to improve a power factor. Japanese Patent Application Laid-Open No. 2002-101550 describes a power factor correction method and a power supply device having a circuit configuration for switching between a full-wave rectifier circuit and a voltage doubler rectifier circuit. Are listed.
[0003]
In the prior art, when the DC current on the rectifier circuit output side or the current value of the short circuit exceeds a predetermined value, the short circuit operation is stopped, the short circuit is protected from overcurrent, and the rectifier circuit configuration is changed to a full-wave rectifier circuit at the same time. The process of switching and returning the system such as the air conditioner motor control device to the initial state is described.
[0004]
[Problems to be solved by the invention]
In the prior art described in Japanese Patent Application Laid-Open No. 2002-101550, there is no description about a protection method in the case where the power cycle cannot be detected as in the case of an abnormality in the AC power supply, or an AC power supply abnormality detection method. In other words, in the power factor correction method in which the short circuit operation of the short circuit is performed in synchronization with the power supply cycle (zero cross signal) of the AC power supply as in the prior art, the power cycle (zero cross signal) of the AC power supply is obtained correctly. Therefore, if a short circuit operation is performed based on an incorrect power supply cycle (zero cross signal), inconveniences such as overcurrent and destruction of a short circuit are caused.
[0005]
In general, since protection at the time of overcurrent requires fast operation, the overcurrent detection circuit is also set to operate instantaneously. For this reason, it is likely to be erroneously detected due to the influence of external noise and the like. However, the prior art does not take into consideration the prevention of malfunction at the time of erroneous detection of the overcurrent detection circuit.
[0006]
Furthermore, in the prior art, the overcurrent protection operation is performed and at the same time the system such as the motor controller for the air conditioner is returned to the initial state, but every time the overcurrent protection operation is activated, the system returns to the initial state. Cannot continue operation. For example, the motor controller for an air conditioner will be described. Once the overcurrent protection operation is activated, the motor controller stops the motor (sets it to the initial state) and starts it again. The apparatus is stopped for 3 minutes to balance the compressor load (pressure). For this reason, an air conditioner will not work for 3 minutes and will give a user discomfort.
[0007]
The objective of this invention is providing the power supply device which detects abnormality of AC power supply and stops short circuit operation.
[0008]
[Means for Solving the Problems]
The power supply apparatus of the present invention correctly detects an abnormality in the AC power supply. AC power supply abnormalities include power outages, power outages, frequency fluctuations, and voltage fluctuations. Further, in Japan, the frequency of commercial AC power supply is 50 Hz and 60 Hz, so that detection and automatic recognition (setting) of the power supply frequency are also necessary.
[0009]
The power supply apparatus of the present invention measures the input cycle of the zero cross signal from the zero cross detection circuit for detecting the zero cross point of the AC power source, and the input cycle is a predetermined value, for example, 8.333 ms when the power source is 60 Hz, and when the power source is 50 Hz. The short-circuit operation of the short-circuit is stopped at 10 ms or in a predetermined range, for example, from 8.3 ms to 8.36 ms for a 60 Hz power source and from 9.96 ms to 10.04 ms for a 50 Hz power source.
[0010]
The power supply device of the present invention stops the short-circuit operation of the short-circuit when the input cycle of the input signal of the zero cross signal changes.
[0011]
The power supply device of the present invention stops the short-circuit operation of the short-circuit when the zero-cross signal input signal is not input for a predetermined time.
[0012]
The power supply device according to the present invention stops the short-circuit operation of the short-circuit when there is no input of the zero-cross signal in the range from the input time point of the zero-cross signal to the second predetermined time after the first predetermined time.
[0013]
The power supply apparatus of the present invention does not accept the input of the next zero cross signal for a predetermined time from the input point of the zero cross signal.
[0014]
The power supply apparatus according to the present invention determines that the zero cross signal is abnormal when there is no input of the zero cross signal in the range from the input point of the zero cross signal to the second predetermined time after the first predetermined time. Does not accept cross signals.
[0015]
The power supply apparatus of the present invention can automatically set a power supply cycle (frequency) by determining a predetermined value or a predetermined range from the input cycle of the detected zero cross signal.
[0016]
The power supply device of the present invention can quickly stop the short-circuit operation of the short-circuit when there is an abnormality in the power supply, and prevent malfunction due to an abnormality in the AC power supply.
[0017]
The power supply device of the present invention receives an overcurrent detection signal only during a period when the short circuit is short-circuited, and performs an overcurrent protection operation including a system stop.
[0018]
The power supply device of the present invention integrates the operation time of the protection operation or counts the number of operations, and stops the system or outputs an abnormal signal to the system when the value reaches a predetermined value. Also, the power supply apparatus of the present invention minimizes the frequency of system shutdown by setting the count as a period or number of times that the protective operation has continued continuously.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a power supply device of the present invention will be described in detail with reference to the drawings. Like reference symbols in the various drawings indicate like elements.
[0020]
The power supply apparatus according to the present embodiment improves the power factor of the power supply by short-circuiting the AC power supply through the reactor once or a plurality of times in the power supply half cycle of the AC power supply. FIG. 1 shows a power supply device 13 of this embodiment. FIG. 1 shows a circuit configuration in the case of a control device for a compressor driving motor of an air conditioner in which an air conditioner compressor driving motor 8 is connected to the inverter circuit 7 of the power supply device 13.
[0021]
1 includes a reactor 2 connected to one terminal of an AC power source 1, a short circuit 3 connected so as to short-circuit the AC power source 1 via the reactor 2, and a reactor 2. A rectifier circuit 4 for converting alternating current to direct current, a changeover switch 5 for switching the rectifier circuit 4 between a full-wave rectifier circuit configuration and a double voltage rectifier circuit configuration, and a smoothing circuit 6. The short circuit 3 and the changeover switch 5 are operated by a short circuit signal 3S and a change signal 5S output from the control circuit 9.
[0022]
As shown in FIG. 1, the control circuit 9 receives the zero cross signal 10S output from the zero cross detection circuit 10 that detects the zero cross point at which the voltage of the AC power supply 1 becomes zero, and the current flowing into the power supply device 13. The input current value 11S output from the input current detection circuit 11 to be detected is input. Each signal is used to control the short circuit 3 and the changeover switch 5.
[0023]
The short circuit 3 is a bidirectional switch that allows a current to flow in both directions. In this embodiment, the short circuit 3 includes a diode bridge circuit and a power semiconductor switching element such as an IGBT or a power MOSFET. The changeover switch 5 is also a bidirectional switch like the short circuit 3, and is a power relay in this embodiment. As shown in FIG. 1, the smoothing circuit 6 has smoothing capacitors connected in series, and an intermediate point is connected to the change-over switch 5. The change-over switch 5 switches between a full-wave rectifier circuit configuration and a voltage doubler rectifier circuit configuration.
[0024]
The number of revolutions of the motor 8 is controlled by software processing in the control circuit 9, and the inverter circuit 7 is driven by the PWM signal 7S. Although a detailed description of the motor control method is omitted in this embodiment, the DC current flowing into the inverter circuit 7 is detected by the resistor 12A and the DC current detection circuit 12, and the DC current value 12S that is the output is controlled. The motor current that is input to the circuit 9 and flows through the motor 8 is reproduced, and vector control is performed based on the motor current information to control the rotational speed and torque of the motor.
[0025]
Next, the power factor improving operation of the power supply circuit of this embodiment and the method for generating a short circuit signal will be described with reference to FIGS. FIG. 2 is a waveform diagram showing temporal changes of the power supply voltage and input current of the AC power supply 1, the zero cross signal 10S, and the short circuit signal 3S. Hereinafter, in the present embodiment, a case where the short-circuit operation is performed once in a half cycle of the power supply frequency will be described.
[0026]
As shown in FIG. 2, the zero cross signal 10S is a rectangular wave signal in which “H” and “L” are inverted at the zero point of the power supply voltage, and the edge portion where the signal is inverted is the zero cross point. The short circuit signal 3S is a pulse having a delay time Td and a pulse width Tp with reference to the edge portion of the zero cross signal 10S. Here, the delay time Td indicates the time from the zero cross point (reference point) to the start of the short-circuit operation, and the pulse width Tp indicates the short-circuit time. When the short circuit 3 is operated with the short circuit signal 3S, as shown in FIG. 2, the current width of the input current of the power supply device 13 is increased, so that the power factor is improved.
[0027]
As the control circuit 9 of this embodiment, a commercially available single chip microcomputer (hereinafter referred to as a microcomputer) was used, and all processes were processed by software. FIG. 3 shows an output compare match register (hereinafter referred to as an OP register) that generates an interrupt when the zero cross signal 10S, the value of the free-run timer in the microcomputer, and the free-run timer value are sequentially compared and matched. And the short circuit signal 3S are shown in time series.
[0028]
When the zero cross signal 10S is inverted at time T0, the data D0 of the delay time Td is written to the OP register by the first interrupt process. At time T1, the value of the free-run timer coincides with the value of the OP register and the second interrupt processing is started, and the short-circuit signal 3S is output “H”, and at the same time, the data D1 having the pulse width Tp is written to the OP register. It is.
[0029]
At time T2, the value of the free-run timer again matches the value of the OP register, the third interrupt process is started, and the short circuit signal 3S is set to “L” output. After this, the short circuit signal 3S maintains the “L” output until the inversion of the zero cross signal 10S occurs again. Here, in the short circuit signal 3S, “H” means short circuit and “L” means open. The above operation is repeated every time the zero cross signal 10S is input (inverted), and a predetermined short-circuit operation is continued every half cycle of the power supply frequency.
[0030]
A protection method in which the power supply device 13 of this embodiment detects an abnormality of the AC power supply 1 and stops the short-circuit operation will be described. FIG. 4 shows a power supply voltage waveform of the AC power supply 1 and a zero cross signal 10S created from the power supply voltage, and an interrupt mask signal for prohibiting an interrupt processing operation that operates in response to the input of the zero cross signal 10S. A case where voltage distortion occurs due to instantaneous power failure or superimposed noise and chattering occurs in the zero cross signal 10S will be described. As shown in FIG. 4, when the zero-cross signal 10S causes chattering, the interrupt process is continuously started and a short-circuit operation at a predetermined timing cannot be performed, and an overcurrent or the like may occur.
[0031]
Therefore, as shown in FIG. 4, the interrupt processing associated with the zero cross signal is not executed for a certain time after the input (inversion) of the zero cross signal 10S. In other words, during the interrupt mask time Tm, the zero cross signal 10S is not executed. An interrupt mask signal that does not accept is generated. With interrupt mask signal processing, even if the power supply environment is bad, it is possible to eliminate malfunction of short circuit operation due to false detection of zero cross signal, prevent overcurrent and system stop, and maintain normal operation. The interrupt mask signal processing is effective even when the output characteristics of the zero cross detection circuit 10 are poor and the zero cross signal 10S has a circuit configuration that causes chattering.
[0032]
A method of monitoring whether the zero cross signal 10S is correctly input to the control circuit 9 at a predetermined cycle will be described with reference to FIG. In Japan, the power supply frequency of commercial AC power supply is 50 Hz and 60 Hz, but this frequency never varies extremely. In this embodiment, a malfunction is mainly prevented when the zero cross signal 10S is generated at a period other than a predetermined period due to a momentary power failure, a lightning surge, or the like.
[0033]
Since the power supply frequency of the commercial AC power supply is stable, once the power supply frequency can be detected, the zero cross signal 10S should be input at a fixed period thereafter. Therefore, the period (time) from the point A in FIG. 5 where the zero cross signal 10S is input to the point C where the zero cross signal 10S is input next is measured, and the period becomes the period of the power supply frequency or a period in the vicinity thereof. If not, the short circuit signal 3S is stopped ("L" output). Alternatively, the zero cross signal 10S is only received at the time C point where the zero cross signal 10S is scheduled to be input next or the time in the vicinity thereof (point B to D) from the time point A when the zero cross signal 10S is input. Input may be accepted. By these methods, it is possible to eliminate an erroneous zero cross signal 10S or noise that enters other than a predetermined period or time.
[0034]
The abnormality determination method for the zero cross signal 10S will be described with reference to the flowchart shown in FIG. The time interval from the input time point A of the zero cross signal 10S shown in FIG. 5A to the next input time point C shown in FIG. 5C is measured in the step of FIG. When the time interval (cycle) matches 8.333 ms (1/60 Hz / 2 (s)) or 10 ms (1/50 Hz / 2 (s)), or the actual power supply frequency is 50 Hz or 60 Hz Since there is a fluctuation of about ± 0.2 Hz, it is determined whether or not it is in the range of 8.30 ms to 8.36 ms including the fluctuation, or in the range of 9.96 ms to 10.04 ms. If Yes, it is determined that the operation is normal, and the process proceeds to Step (U) and Step (E). If No, the operation is determined to be abnormal and the process proceeds to Step (O) to stop the short-circuit operation. Here, if it is determined whether the power source is 50 Hz or 60 Hz using the period measured in step (u), the power source frequency can be automatically detected.
[0035]
Further, since the power supply frequency of the commercial AC power supply is fixed if the installation location is fixed, the power supply frequency does not change during operation, so that the power supply cycle itself is a power supply abnormality. Therefore, the short-circuit operation is also stopped when the measurement frequency changes during operation. Thereby, abnormal operation due to an erroneous signal input at the same timing as the accidental comparison value (cycle) can be prevented. FIG. 7 shows a flowchart in this case.
[0036]
A method of monitoring whether the zero cross signal 10S is correctly input at a predetermined cycle will be described with reference to FIG. The zero cross signal 10S input is not accepted during the period from the input time point A to the time point B of the zero cross signal 10S and the period after the time point D. In other words, the input of the zero cross signal 10S is permitted only in the range from the time point B to the time point D, and the others are not permitted. Alternatively, when there is no input of the zero cross signal 10S in the time range in which the input of the zero cross signal 10S is permitted, the short circuit operation is stopped. In FIG. 8, taking as an example the case where the power supply frequency is 50 Hz, the time width T55 from the time point A to the time point B is set to correspond to a half cycle of the power supply frequency 55 Hz so as to be able to cope with a certain degree of frequency fluctuation. A time width T45 up to the time point D is set to correspond to a half cycle of a power supply frequency of 45 Hz. When the power supply frequency is f (Hz), the time width from the time point A in FIG. 8 may be determined in the range of f ± 0.1 f as described above.
[0037]
FIG. 9 shows a zero cross signal 10S, a short circuit signal 3S, a short circuit operation permission signal for permitting / stopping the short circuit operation from the input state of the zero cross signal 10S, and an error in the host system when the power supply abnormal state continues continuously. The timing chart shows the relationship with the power supply abnormality signal that informs the user. FIG. 9 shows a state where a power failure occurs at time T2 and no zero cross signal 10S is input after time T2 during operation at a power supply frequency of 50 Hz.
[0038]
In this case, since the zero cross signal 10S is correctly input until time T2, the short circuit signal 3S is output. However, since the zero cross signal 10S is not input at time T3, the short circuit operation is stopped. If the zero cross signal 10S is not input after time T5, the short circuit operation is stopped and a power supply abnormality signal is notified to the host system. In this embodiment, the operation of the motor that drives the compressor is stopped. Here, the time T5 is a time when a preset time Tw has elapsed from the last zero cross signal 10S input time T2. In this embodiment, a case where the power cycle is set to three times is shown. Thus, the short-circuit operation is stopped when the zero cross signal 10S is not input for a predetermined time or more, and at the same time, the system can be stopped by notifying the host system of the abnormality. Further, since the same operation is performed when the zero-cross detection circuit 10 fails, it can be used for determining the abnormality of the zero-cross detection circuit.
[0039]
The malfunction prevention method of the overcurrent protection operation accompanying the erroneous detection of the overcurrent detection circuit will be described with reference to FIG. 10 shows a zero cross signal 10S, a short circuit signal 3S, an overcurrent detection signal detected in the input current detection circuit 11 of FIG. 1, an overcurrent flag used in the microcomputer, and an overcurrent counter (overcurrent counter). It is a timing chart showing the relationship between the count of the number of protection operations) and an overcurrent error signal that informs the host system. FIG. 10 shows a state in which external noise is superimposed on an overcurrent signal. A signal indicated by “F” is a false detection signal, and a signal indicated by “T” is a normal overcurrent signal.
[0040]
As shown in FIG. 10, when an overcurrent protection operation is performed in response to an erroneous overcurrent signal, stable control cannot be performed as a system. Therefore, the short-circuit signal 3S is set to “H”, that is, the short-circuit circuit 3 is set to react only to the overcurrent signal input during the short-circuit. With this setting, the overcurrent protection is not activated when the overcurrent signal “F” shown in FIG. 10 is input, and the protection operation is performed only when the overcurrent state is really achieved, so that stable control can be performed. Here, when the overcurrent protection operation is executed, the overcurrent flag in the microcomputer changes to the “H” state as shown in FIG.
[0041]
In FIG. 10, when the overcurrent protection operation is executed, the overcurrent flag is set to “H”. Thereafter, if the overcurrent flag is “H” when the next zero cross signal 10S is input, the overcurrent counter is decremented by one and simultaneously the overcurrent flag is cleared. When the overcurrent flag is “L”, the overcurrent counter is returned to the initial value. By repeating this operation, the number of times (or time) at which the protection operation is continuously executed is measured. When the overcurrent counter reaches 0, an overcurrent error signal is output to the host system to notify the abnormality. In this embodiment, the operation of the motor that drives the compressor is stopped.
[0042]
As described above, frequent system stoppage when the protection operation occurs can be prevented, and stable system operation can be performed. In addition, the system can be surely stopped in the event of an abnormality that must be stopped. Needless to say, this protection operation can also be applied during a power failure protection operation.
[0043]
In this embodiment, all the protective operations described above are always performed, and safety and stability are ensured. The power supply device of the present embodiment is suitable for driving a motor of an air conditioner or a compressor of a refrigerator.
[0044]
【The invention's effect】
As described above, when the power supply device of the present invention is used, protection when an AC power supply is abnormal can be easily performed. Further, even in a large environment such as external noise, the protection operation can be prevented from malfunctioning, which can contribute to the stability of the system. In addition, frequent system stoppage when a protective operation occurs can be prevented and stable system operation can be achieved.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a circuit configuration of a motor control device according to an embodiment.
FIG. 2 is an explanatory diagram of a power factor improvement and a generation method of a short circuit signal of the power supply device according to the embodiment.
FIG. 3 is an explanatory diagram of a method for creating a short circuit signal of the power supply device according to the embodiment.
FIG. 4 is an explanatory diagram of an interrupt mask signal of the power supply device according to the embodiment.
FIG. 5 is an explanatory diagram of power cycle abnormality protection of the power supply device according to the embodiment.
FIG. 6 is a flowchart of determining a zero cross signal abnormality of the power supply device according to the embodiment.
FIG. 7 is a flowchart of another method of determining a zero cross signal abnormality of the power supply device according to the embodiment.
FIG. 8 is an explanatory diagram of power cycle protection of the power supply device according to the embodiment.
FIG. 9 is an explanatory diagram of protection during a power failure of the power supply device according to the embodiment.
FIG. 10 is an explanatory diagram of overcurrent protection of the power supply device according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... AC power source, 2 ... Reactor, 3 ... Short circuit, 4 ... Rectifier circuit, 5 ... Changeover switch, 6 ... Smoothing circuit, 7 ... Inverter circuit, 8 ... Motor, 9 ... Control circuit, 10 ... Zero cross detection circuit, DESCRIPTION OF SYMBOLS 11 ... Input current detection circuit, 12 ... DC current detection circuit, 3S ... Short circuit signal, 5S ... Switching signal, 6S ... DC voltage value, 7S ... Inverter PWM signal, 10S ... Zero cross signal, 11S ... Input current value, 12S ... DC current value.

Claims (1)

A rectifier circuit that converts AC power into DC, a zero-cross detection circuit that detects a zero-cross point of the AC power and outputs a zero-cross signal, and short-circuits the AC power via a reactor based on the zero-cross signal In a power supply device comprising: a short circuit; a smoothing circuit connected to an output terminal of the rectifying circuit; an inverter circuit that drives a motor connected to the smoothing circuit; and a control circuit that outputs a control signal to the inverter circuit ,
The control circuit detects an overcurrent from the input current detection signal, and based on the overcurrent detection signal output from the overcurrent detection circuit, stops the short-circuit operation of the short-circuit, and the host system An overcurrent stop circuit for notifying an overcurrent state, and when the zero cross signal abnormality or the operation of the overcurrent prevention circuit occurs continuously for a predetermined period and occurs a predetermined number of times. A power supply device characterized by stopping operation.

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