JPH11187646A - AC current control device and control method thereof - Google Patents

Abstract

(57) Abstract: An AC current control device for adjusting a gain so as to obtain a predetermined control response in accordance with an actual power supply impedance and an actual reactor inductance value is provided. SOLUTION: Based on a current flowing through a rectifier circuit composed of at least a reactor 3, a diode bridge 2, a smoothing capacitor 5, and a switching element 8 for converting a voltage from an AC power supply 1 to a DC voltage and the converted DC voltage, In an AC current control device that calculates a PWM duty according to a set current control gain and performs PWM control on the switching element 8 in order to perform feedback control of the current, when operated, the AC power supply 1 and the rectifier circuit are electrically connected. And a current control gain setting means 15 that operates the relay 14 to calculate and set a current control gain based on a change in the DC voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC current control device for controlling an input current of an AC power supply to a desired waveform.

[0002]

2. Description of the Related Art FIG. 10 is an overall configuration diagram showing the configuration of a conventional AC control device. In FIG. 10, 1 is an AC power supply,
2 is a diode bridge connected to the AC power supply 1, 3 is a reactor connected to the positive side (cathode side) of the diode bridge 2, 7 is a reverse blocking diode connected to the reactor 3, and 9 is a negative side of the diode bridge 2. (Anode side) Current detector connected to 8, relay 1
A switching element connected between 4 and the current detector 9;
5 is a smoothing capacitor connected to the output side of the reverse blocking diode 4 and the current detector 9, and 18 is a load connected in parallel to the smoothing capacitor.

Reference numeral 4 denotes converter control means. 12
Is a voltage phase detecting means connected to the AC power supply 1, 13 is a sine wave generating means connected to the voltage phase detecting means 12, 6 is connected to the smoothing capacitor 5, and the DC voltage Vdc applied to the smoothing capacitor 5 A voltage control unit to which the DC voltage Vdc * is input, 17 is a multiplication unit connected to the sine wave generation unit 13 and the voltage control unit 6, and 11A is a multiplication unit 17
Current control means 10 receiving a signal from the current detector 9 and a signal from the current control means 11A,
PWM means for outputting an M signal.

The AC power generated from the AC power supply 1 is rectified through the diode bridge 2, the reactor 3, and the reverse blocking diode 7, and supplies DC power to the load 18.
Each means of the converter control means 4, as shown below,
The switching element 8 is controlled based on the detected input current such that the power factor becomes 1. The voltage phase detecting means 12 detects the power supply voltage and outputs the current voltage phase θ (where the voltage phase θ is a repetition phase of a power supply half-wave cycle: 0 ≦ θ <π). The sine wave generator 13 outputs sinθ based on the voltage phase θ output from the voltage phase detector 12. The voltage control means 6 detects a DC voltage Vdc applied between both electrodes of the smoothing capacitor 5, calculates an amplitude command value of (input current) based on a deviation between the DC voltage Vdc and the target DC voltage Vdc *, and outputs I do. The current detector 9 detects the input current I rectified by the diode bridge 2.

The multiplying means 17 calculates and outputs an input current command value I * based on the amplitude command value output from the voltage control means 6 and the sin θ output from the sine wave creating means 13. The current control unit 11A calculates a deviation between the input current I output from the current detector 9 and the input current command value I * output from the multiplication unit 17, and multiplies the deviation by a predetermined gain K. Is output as the PWM duty. The PWM means 10 converts the PWM duty output from the current control means 11A into a switching element on / off timing signal (hereinafter, referred to as a PWM signal) having a predetermined carrier frequency to control the switching element 8 on / off. As a result, the waveform of the input current I is controlled to be substantially a sine wave.

Here, the current control gain K of the current control means 11A is a fixed value set in advance. A transfer function of a current control system, which is an index of a control response in the device, will be described for an example of a method of setting the current control gain K.
When the resistance of the power supply impedance and the reactor impedance and the power supply voltage are neglected, it is expressed by the following equation (1). Here, L is the power source impedance and the inductance of the reactor, and G (s) is the current control system closed loop transfer function. G (s) = 1 / (L / K · s + 1) (1)

Therefore, when the required current control response of the device, the reference power supply impedance and the reference inductance of the reactor are determined, the lower limit value of the current control gain K is determined from equation (1). The upper limit value of the current control gain K is determined by the start limit of the current oscillation (a value such that the gain due to the current oscillation does not exceed 0 dB) due to the influence of the PWM frequency and the delay time of the control system.

FIG. 11 is a reactor current waveform diagram based on the difference in the value of the current control gain K. Here, if the preset current control gain K is within an optimum range, the waveform of the actual current becomes stable as shown in FIG. 11B. However, when the value of the current control gain K is set to an inappropriate value with respect to the power supply impedance of the use environment or the like, when the current control gain is insufficient, FIG.
As described above, the current waveform of the actual current is distorted, and the power factor is reduced.
When the current control gain is excessive, the current peak increases as shown in FIG. 11C, and the controllability deteriorates.

[0009]

Since the conventional AC current control device is configured as described above, when setting the current control gain K, if there is an error between the assumed power supply impedance and the actual power supply impedance. Depending on the use environment, a predetermined control response cannot be obtained, and the control becomes unstable.
Also, there is a problem that the control becomes unstable similarly even if an error occurs between the design value and the actual value of the reactor.

The present invention has been made to solve the above-mentioned problems, and adjusts a gain so that a predetermined control response can be obtained in accordance with an actual power supply impedance and an actual inductance of a reactor. An object is to obtain an AC current control device.

[0011]

According to the present invention, there is provided an AC current control apparatus for converting a voltage applied from an AC power supply into a DC voltage, the rectifier circuit comprising at least a reactor, a diode, a smoothing capacitor, and a switching element. In order to feedback-control an input current supplied by an AC power supply based on the flowing current and the converted DC voltage, a PWM duty according to a set current control gain is calculated, and the switching element is PWM-controlled based on the PWM duty. In the AC current control device, when operated, a relay circuit that electrically connects the AC power supply and the rectifier circuit, and a relay circuit that operates to electrically connect the AC power supply and the rectifier circuit, and that Based on the change to stability, the power of the set environment and the impedance of the set reactor And a current control gain setting means for setting a current control gain in consideration of the dance.

Further, the current control gain setting means of the AC current control device according to the present invention is characterized in that the DC voltage value becomes a predetermined voltage value after the AC power supply and the rectifier circuit are electrically connected by the relay circuit. The change in the DC voltage is detected as a change in the DC voltage. At this time, the larger the impedance, the lower the slope at which the DC voltage increases in order to stabilize the DC voltage. In order to make the value of the current control gain higher as the time is longer, the correlation between the time and the value of the current control gain is set to be positive.

[0013] The current control gain setting means of the AC current control device according to the present invention is characterized in that the DC voltage value from the time when the AC power supply and the rectifier circuit are electrically connected by the relay circuit until a predetermined time has elapsed. The amount of change is calculated as a change in the DC voltage. At this time, the larger the impedance of the current control gain, the lower the slope of the voltage change until the DC voltage stabilizes. The lower the voltage, the higher the value of the current control gain. Therefore, the correlation between the amount of change and the value of the current control gain is set to be negative.

Further, the current control gain setting means of the AC current control device according to the present invention is provided for performing the measurement in consideration of the influence on the DC voltage based on the phase of the AC power supply when the DC voltage is not stable. When the phase during the half cycle of the AC power supply reaches a predetermined phase, the relay circuit starts the electrical connection between the AC power supply and the rectifier circuit.

In the relay circuit of the AC current control device according to the present invention, the first relay means having a resistance connected in series and the second relay means having no resistance connected are connected in parallel. The current control gain setting means protects the rectifier circuit by electrically connecting the AC power supply and the rectifier circuit by the first relay means until the current control gain is set, and when the PWM control is started. The AC power supply and the rectifier circuit are electrically connected by the second relay means.

Further, the AC current control device according to the present invention converts a current applied to a rectifier circuit comprising at least a reactor, a diode, a smoothing capacitor and a switching element, which converts a voltage applied by an AC power supply into a DC voltage. Based on the DC voltage obtained, in order to feedback control the input current supplied by the AC power supply,
In an AC current control device that calculates a PWM duty according to a set current control gain and performs PWM control on a switching element based on the PWM duty, a reference duty generation unit that generates a predetermined reference PWM duty, and a reference duty generation A current control gain for setting a current control gain in consideration of a power supply of a set environment and an impedance of a set reactor based on a change in DC voltage when the switching element is driven at a reference PWM duty generated by the means; Setting means.

Further, the current control gain setting means of the AC current control device according to the present invention is characterized in that the time from when the switching element is driven at the reference PWM duty to when the DC voltage value reaches a predetermined voltage value is set to DC. A change in voltage is detected. At this time, the current control gain uses the fact that the larger the impedance, the lower the slope of the DC voltage rise (that is, the longer it takes to reach a certain voltage). In order to increase the value of the current control gain, the correlation between the time and the value of the current control gain is set to be positive.

Further, the current control gain setting means of the AC current control device according to the present invention is characterized in that the change amount of the DC voltage value from the time when the switching element is driven with the reference PWM duty until the predetermined time has elapsed is determined. The current control gain is calculated as a change. At this time, the larger the impedance, the lower the slope of the voltage change until the DC voltage becomes stable (that is, within a certain period of time, the larger the impedance, the lower the voltage). To take advantage of this fact, in order to increase the value of the current control gain as the voltage is lower, the correlation between the amount of change and the value of the current control gain is set to be negative.

Further, the current control gain setting means of the AC current control device according to the present invention performs the measurement in consideration of the influence on the DC voltage based on the phase of the AC power supply. When a predetermined phase is reached, the reference P
The driving of the switching element at the WM duty is started.

Further, in the control method of the AC current control device according to the present invention, the AC power supply is electrically connected to a rectifier circuit including at least a reactor, a diode, a smoothing capacitor, and a switching element, and is applied by the AC power supply. Converting the applied voltage to a DC voltage, a step of measuring the time from when the AC power supply and the rectifier circuit are electrically connected to when the DC voltage reaches a predetermined value, and based on the measured time. Calculating and setting the current control gain;
The method includes a step of calculating a PWM duty based on the set current control gain, and a step of performing PWM control of the switching element based on the PWM duty and performing feedback control of an input current supplied from an AC power supply.

According to a control method of an AC current control device according to the present invention, an AC power supply is electrically connected to a rectifier circuit including at least a reactor, a diode, a smoothing capacitor, and a switching element, and is applied by the AC power supply. Converting the voltage to be applied to a DC voltage, measuring the value of the DC voltage after a predetermined time has passed since the AC power supply and the rectifier circuit are electrically connected, and calculating the amount of change in the DC voltage, Setting a current control gain based on the calculated amount of change in DC voltage, calculating a PWM duty based on the set current control gain, performing PWM control on the switching element based on the PWM duty, and Feedback controlling the supplied input current.

In a control method of an AC current control device according to the present invention, an AC power supply is electrically connected to a rectifier circuit including at least a reactor, a diode, a smoothing capacitor, and a switching element, and the AC power supply is applied by the AC power supply. A step of converting the applied voltage to a DC voltage, a step of generating a reference PWM duty to perform PWM control of the switching element, and a step of performing feedback control of an input current supplied from an AC power supply. Measuring a time until the voltage reaches a predetermined value; setting a current control gain based on the measured time; calculating a PWM duty based on the set current control gain; PWM control of a switching element based on a PWM duty based on a control gain And it has a door.

In the control method of the AC current control device according to the present invention, the AC power supply is electrically connected to a rectifier circuit including at least a reactor, a diode, a smoothing capacitor and a switching element, and the AC power supply is applied by the AC power supply. A step of converting the applied voltage into a DC voltage, a step of generating a reference PWM duty to perform PWM control of the switching element, and a step of performing feedback control of an input current supplied from an AC power supply. Measuring the value of the DC voltage after a lapse of time, calculating a change amount of the DC voltage, setting a current control gain based on the calculated change amount of the DC voltage, and based on the set current control gain. Calculating the PWM duty; and controlling the PWM duty based on the PWM duty based on the set current control gain. The switching element and a step of PWM control.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is an overall configuration diagram of an AC current control device according to a first embodiment of the present invention. In the figure, those having the same reference numerals as those in FIG. 10 perform the same operations as those of the conventional AC current control device, and thus the description thereof is omitted. In the figure, reference numeral 14 denotes a relay circuit (hereinafter referred to as a relay) which is connected in series between the reactor 3 and the reverse blocking diode 7 and which is turned on by the current control gain setting means 15 during operation of the apparatus. Reference numeral 15 denotes a current control gain setting unit that measures time by incorporating a timer, and sets a current control gain K based on the time and a change in DC voltage during operation of the apparatus. Reference numeral 11 denotes current control means for calculating a PWM duty based on the current control gain K set in the current control gain setting means 15. Reference numeral 16 denotes the impedance of the power distribution system from the power supply to the device.

FIG. 2 is a diagram showing a change in the DC voltage when the relay 14 is turned on (ie, when the operation of the AC current control device is started). This figure shows that, assuming that the power supply voltage is constant, the change in the flowing current decreases as the impedance increases, so that the change in the DC voltage also decreases, and it takes time for the smoothing capacitor 5 to be charged. I have. In the present embodiment, the impedance of the AC power supply 1 and the reactor 3 is estimated based on the change in the DC voltage at the time of startup, and the AC current control is performed by setting the optimum current control gain K based on the impedance. is there.

FIG. 3 is a flowchart showing a setting sequence of the current control gain K. The operation of the current control gain setting means 15 will be described with reference to FIG. When supplying power to the load (at the time of starting), the current control gain setting means 1
5 turns on the relay 14 (S31). When the relay 14 provided in series with the circuit is turned on and the circuit is connected, the operation (current control) of the device is started. The current control gain setting means 15 starts measuring time, and measures until the value of the DC voltage Vdc becomes larger than the value of the predetermined voltage Vr (S32). DC voltage Vdc
Is the arrival time T (S33), the current control gain K is determined by substituting the arrival time T into the following equation (2) (S3).
4) Output to the current control means 11. Here, Tnom is a reference value of the arrival time stored in advance, and Knom is a value of the reference current control gain stored in advance. K = Knom ・ T / Tnom ... (2)

The current control means 11 outputs a PWM duty based on the current control gain K input from the current control gain setting means 15, similarly to the conventional AC current control device, and the waveform of the input current I is sinusoidal. Control is performed so as to form a wave (S35). In the equation (2), when the three impedances of the AC power supply 1 and the reactor are small, the current control gain K becomes small, and conversely, the AC power supply 1 and the reactor 3
Is set so that the current control gain K increases. Therefore, it is possible to realize a stable AC current control device in which the control response is hardly deteriorated due to a change in installation environment or a variation in reactor performance. Here, the calculation of the current control gain K is performed by the equation (2). However, the calculation is not limited thereto, and K is a positive correlation with the predetermined voltage arrival time T (K is large if T is large). ), And the current control gain K may be adjusted to improve control responsiveness.

FIG. 4 is a flowchart showing another setting sequence of the current control gain K. Another operation of the current control gain setting means 15 will be described based on FIG.
When supplying power to the load (at startup), the current control gain setting means 15 turns on the relay 14 and calculates the DC voltage in the initial state (S41). Current control gain setting means 15
Measures a predetermined time Ta (S4).
2). After the elapse of the predetermined time Ta, the DC voltage Vdc is measured, the DC voltage variation ΔV is calculated (S43), and the current control gain K is obtained by substituting the DC voltage change ΔV into the following equation (3) (S44). Output. Here, ΔVnom is a reference value of a DC voltage change amount, and Knom is a value of a reference current control gain. K = Knom × ΔVnom / ΔV (3)

The current control means 11 outputs a PWM duty based on the current control gain K input from the current control gain setting means 15, similarly to the conventional AC current control device, and the waveform of the input current I is sinusoidal. Control is performed so as to form a wave (S45). Here, the calculation of the current control gain K is performed by the equation (3). However, the present invention is not limited to this. The current control gain K has a negative correlation with the DC voltage variation ΔV (if ΔV is large, (For example, K may be reduced), and the current control gain K may be adjusted to improve the control response.

Although the influence has been neglected in the above description, since the power supply voltage is alternating current, the DC voltage at the time of turning on the power actually rises while pulsating under the influence of the input voltage which changes in the power supply cycle. That is, the change characteristics of the DC voltage
Depends on the power supply voltage phase at the ON timing, and the detected value changes due to the difference in the phase. Therefore, if the ON timing of the relay 14 varies, the power supply voltage phase at the time of the ON timing of the relay 14 also fluctuates, causing an error in the calculation of the DC voltage change characteristic in the measurement sequence. To avoid this, if the current control gain setting means 15 turns on the relay 14 at a predetermined phase during a half cycle of the AC power supply, the change characteristic can be detected with higher accuracy.

FIG. 5 is an example of a configuration diagram of the relay 14. In the figure, a relay 14a and a resistor 14a1 are connected in series, and a relay 14a and a resistor 14a1
b is connected in parallel. The flow of a large amount of current in the initial state adversely affects each device such as the smoothing capacitor 5, so that the current control gain setting means 15 turns on the relay 14a in S1 to reduce the current control gain K. After calculating and turning on the relay 14b, the current control is started to protect each device constituting the circuit.

As described above, according to the first embodiment,
The current control gain setting means 15 turns on the relay 14, starts the measurement of the value of the DC voltage value Vdc at the time of starting and the measurement of the time, and the DC voltage value Vdc becomes larger than the predetermined voltage Vr. The current control gain K is calculated based on the arrival time T, the arrival time T, the reference value Tnom of the arrival time stored in advance, and the reference current control gain value Knom. 11
Outputs a value obtained by multiplying the deviation between the input current I and the input current command value I * output from the multiplying means 17 by the current control gain K calculated by the current control gain setting means 15 as a PWM duty. 10 is a current control means 11
The AC current control is performed by controlling the switching element 8 to be turned on / off based on the PWM duty output by the controller, so that it is possible to perform the AC current control based on the setting environment and the performance of the reactor. A stable AC current control device in which the control response is less deteriorated due to reactor performance variation can be realized without impairing the startup time. Also, the current control gain setting means 15
Is turned on, the measurement of the value of the DC voltage Vdc at the time of startup and the measurement of time are started, the value of the DC voltage Vdc after a predetermined time Ta is measured, and the initial state (here, 0 V ) Is calculated, and a current control gain K is calculated based on a reference value ΔVnom of the DC voltage change amount and a value Knom of the reference current control gain stored in advance, and the current control means 11 A value obtained by multiplying the deviation between I and the input current command value I * outputted from the multiplying means 17 by the current control gain K calculated by the current control gain setting means 15 is output as a PWM duty, and the PWM means 10
However, since the switching element 8 is turned on / off based on the PWM duty output by the current control means 11 to perform the AC current control, the AC current control based on the setting environment and the performance of the reactor can be performed. As a result, it is possible to realize a stable AC current control device in which the control response is less deteriorated due to a change in the installation environment and a variation in reactor performance.
Further, since the ON timing of the relay 14 is performed at a predetermined phase during a half cycle of the AC power supply, the change characteristic can be detected with higher accuracy.

Embodiment 2 FIG. FIG. 6 is an overall configuration diagram of an AC current control device according to a second embodiment of the present invention. In the figure, components having the same reference numerals as those in FIG. 1 perform the same operations as those of the AC current control device in FIG. In FIG. 6, reference numeral 18 denotes a reference duty generating means for outputting a reference PWM duty. The present embodiment monitors a DC voltage change during operation based on the reference PWM duty, estimates the impedance of the AC power supply 1 and the reactor 3, and determines an optimal current control gain K based on the impedance. The AC current control is performed by setting.

FIG. 7 is a diagram showing a change in the DC voltage when the motor is operated with the reference PWM duty generated by the reference duty generating means 18. Assuming that the power supply voltage is constant, the change in the flowing current decreases as the impedance increases, so that the DC voltage change also decreases, and it takes time for the smoothing capacitor 5 to be charged.

FIG. 8 is a flowchart showing a setting sequence of the current control gain K. The operation of the current control gain setting means 15 will be described with reference to FIG. After the AC power supply 1 is started and the power is supplied to the device and the DC voltage is stabilized after a certain time, the current control gain setting means 15 switches the changeover switch 19 between the reference duty generating means 18 and the PWM.
Means 10 and the reference duty generating means 18
To send a signal of the reference PWM duty (S
81). By current control by the reference PWM duty,
The smoothing capacitor 5 is boosted. The current control gain setting means 15 starts measuring time after the signal of the reference PWM duty is transmitted, and measures until the value of the DC voltage Vdc becomes larger than the value of the predetermined voltage Vr (S82). . Assuming that the time when the value of the DC voltage Vdc becomes larger than the value of the predetermined voltage Vr is the arrival time T (S83), the stored reference time value Tnom and the reference current control gain value Knom are stored in advance. In the same manner as in the first embodiment, the current control gain K is obtained by substituting into equation (2) to obtain the current control gain K (S84), output to the current control means 11, and switch the changeover switch 19 to switch the current control means 1
1 and the PWM means 10 are connected. The current control means 11 outputs a PWM duty based on the current control gain K input from the current control gain setting means 15, similarly to the conventional AC current control device, so that the waveform of the input current I becomes a sine wave. (S85).

FIG. 9 is a flowchart showing another current control gain K setting sequence. Another operation of the current control gain setting means 15 will be described based on FIG.
After the AC power supply 1 is started and power is supplied to the device and the DC voltage is stabilized after a certain period of time, the current control gain setting means 15 switches the changeover switch 19 to the reference duty generation means 18
And the PWM means 10 are connected to send a signal of the reference PWM duty to the reference duty generating means 18 (S91). The voltage of the smoothing capacitor 5 is boosted by the current control based on the reference PWM duty. The current control gain setting means 15 measures the time from when the signal of the reference PWM duty is transmitted until a predetermined time Ta is reached (S92). After a lapse of a predetermined time Ta,
Measures the DC voltage Vdc, the initial state (V ₀ in FIG. 7)
Is calculated (S93). Calculated DC voltage change amount ΔV, DC voltage change amount reference value ΔV
Based on nom and the value of the reference current control gain Knom,
The current control gain K is obtained by substituting into the equation (3) (S9
4) Output to the current control means 11 and switch the changeover switch 19 so that the current control means 11 and the PWM means 10 are connected. The current control means 11 is based on the current control gain K input from the current control gain setting means 15, as in the case of the AC current control device of the first embodiment.
The PWM duty is output, and control is performed so that the waveform of the input current I becomes a sine wave (S95).

Here, since the voltage controlled by the reference PWM duty is not constant, the DC voltage increases while pulsating in the PWM control by the reference PWM duty.
Therefore, the change characteristic of the DC voltage also depends on the power supply voltage phase of the start timing at which the reference duty generation means 18 generates the reference PWM duty, and the detected value changes depending on the difference in the phase. Therefore, if the startup timing varies, the power supply voltage phase at the startup timing also varies, which causes an error in the calculation of the DC voltage change characteristic in the measurement sequence. If the start timing is set at a predetermined phase during a half cycle of the AC power supply to avoid this, the change characteristic can be detected with higher accuracy.

As described above, according to the second embodiment,
The current control gain setting means 15 connects the changeover switch 19 to the reference duty generation means 18 side and switches the switching element 8 based on the signal of the reference PWM duty.
Control, and at the same time, the measurement of the value of the DC voltage value Vdc and the measurement of the time are started, and the arrival time T until the DC voltage value Vdc becomes larger than the predetermined voltage Vr is determined. The current control gain K is calculated based on the measured arrival time T, the reference value Tnom of the arrival time stored in advance, and the reference current control gain value Knom. A value obtained by multiplying the deviation from the input current command value I * output from the current control unit 17 by the current control gain K calculated by the current control gain setting unit 15 is output as a PWM duty.
However, since the switching element 8 is turned on / off based on the PWM duty output by the current control means 11 to perform the AC current control, the AC current control based on the setting environment and the performance of the reactor can be performed. It is possible to realize a stable AC current control device in which the control response is little deteriorated due to a change in installation environment or a variation in reactor performance, without the need for providing a relay, at low cost, and without impairing the startup time. In addition, when the DC voltage value Vdc is measured, the voltage is not boosted so as to exceed the predetermined voltage Vr. Therefore, the upper limit of the DC voltage is set, so that it is possible to prevent the DC voltage from being overvoltage and to operate safely. . Further, the current control gain setting means 15 controls the switching element 8 based on the signal of the reference PWM duty by performing PWM control.
A value of a DC voltage value Vdc after a predetermined time Ta is measured, a difference ΔV from the initial state is calculated, and a previously stored reference value ΔVnom of the DC voltage change amount and a value of the reference current control gain are stored. The current control gain K is calculated based on Knom, and the current control means 11 calculates the deviation between the input current I and the input current command value I * output from the multiplication means 17 by the current control gain setting means 15. A value multiplied by the current control gain K is output as a PWM duty, and P
Since the WM means 10 performs on / off control of the switching element 8 based on the PWM duty output from the current control means 11 to perform the AC current control, the processing up to the AC current control by the set current control gain K is performed. The time is constant, and the apparent operation is stabilized. Furthermore, the switching element 8 based on the signal of the reference PWM duty
Since the PWM control is started at a predetermined phase during a half cycle of the cycle of the AC power supply, the change characteristic can be detected with higher accuracy.

Embodiment 3 In the above-described embodiment, the example of the boost chopper type is shown as the converter circuit portion of the AC current control device. However, the present invention is not limited to this, and the converter circuit may be a full bridge type or a step-down chopper type. Implementation is possible as well.

Although the current command is made to be a sine wave, the present invention is not limited to this, and the current command can be realized in any waveform.
Although the power supply has been described as a single-phase power supply, the power supply can be similarly realized by a polyphase alternating current.

In the above embodiments, the time required for determining the current control gain K can be shortened to several milliseconds to several hundred milliseconds depending on the pulse interval. (Eg air conditioners, refrigerators,
Even when the present invention is applied to a power supply circuit of a UPS (uninterruptible power supply) or the like, the influence on the starting characteristics of the device can be extremely reduced.

[0042]

As described above, according to the present invention, the current control gain setting means electrically connects the AC power supply and the rectifier circuit by the relay, and controls the current control based on the change until the DC voltage becomes stable. The gain is calculated and set, and the feedback control of the input current is performed by the PWM control. Therefore, the stable AC current with little deterioration of the control response in consideration of the power supply of the set environment and the impedance of the set reactor is considered. The control device can be realized without impairing the startup time.

Further, according to the present invention, the current control gain setting means sets the time from when the AC power supply and the rectifier circuit are electrically connected by the relay circuit until the DC voltage value reaches the predetermined voltage value. Since the time is detected immediately after connection as a change in the DC voltage, the current control gain can be calculated and set based on the change in the DC voltage without impairing the startup time.

Further, according to the present invention, the current control gain setting means determines the amount of change in the DC voltage value from the time when the AC power supply and the rectifier circuit are electrically connected by the relay circuit until a predetermined time. Since the change in the DC voltage is calculated immediately after connection, the current control gain can be calculated and set based on the change in the DC voltage without impairing the startup time.

Further, according to the present invention, the current control gain setting means starts the electrical connection between the AC power supply and the rectifier circuit by the relay circuit when the phase during the half cycle of the AC power supply becomes a predetermined phase. Because the DC voltage is not stable, the measurement can be performed in consideration of the influence on the DC voltage based on the phase of the AC power supply. Control responsiveness can be obtained.

According to the present invention, the current control gain setting means electrically connects the AC power supply and the rectifier circuit by the first relay means until the current control gain is set, and the PWM control starts. Then, since the AC power supply and the rectifier circuit are electrically connected by the second relay means, an excessive current does not flow through the rectifier circuit at the time of startup, and the rectifier circuit can be protected.

Further, according to the present invention, the current control gain setting means determines whether or not the reference P is generated by the reference duty generating means.
The current control gain is calculated and set based on the change in the DC voltage by the PWM control based on the WM duty, and
Since the input current feedback control is performed by M control, it is necessary to provide a stable AC current control device with little deterioration of control response considering the power supply of the set environment and the impedance of the set reactor, and a relay circuit. It can be realized inexpensively and without losing the startup time.

Also, according to the present invention, the current control gain setting means sets the time from when the switching element is driven at the reference PWM duty to when the DC voltage value reaches a predetermined voltage value to the change of the DC voltage. Since the DC voltage is not boosted so that it exceeds a predetermined voltage value when measuring the DC voltage, the upper limit of the DC voltage is set, thereby preventing an overvoltage of the DC voltage. Can work safely.

Further, according to the present invention, the current control gain setting means calculates the amount of change in the DC voltage value from the time when the switching element is driven with the reference PWM duty until a predetermined time as the change in the DC voltage. Therefore, the processing time until the AC current control by the set current control gain is constant, and the apparent operation is stabilized.

Further, according to the present invention, the current control gain setting means starts driving the switching element at the reference PWM duty when the phase during the half cycle of the AC power supply becomes a predetermined phase. Therefore, the measurement can be performed in consideration of the influence on the DC voltage based on the phase of the AC power supply, a change in the DC current with high accuracy can be detected, and better control responsiveness can be obtained.

According to the present invention, the AC power supply and the rectifier circuit are electrically connected, and the time from when the AC power supply and the rectifier circuit are electrically connected to when the DC voltage reaches a predetermined value is reduced. Since the current control gain is measured and calculated, the current control gain is calculated, the switching element is PWM-controlled based on the PWM duty based on the set current control gain, and the input current supplied from the AC power supply is feedback-controlled. In addition, a stable AC current control device with little deterioration of the control response in consideration of the power supply of the set environment and the impedance of the set reactor can be easily realized immediately after the startup without impairing the startup time.

Further, according to the present invention, the AC power supply and the rectifier circuit are electrically connected, and the value of the DC voltage is measured after a predetermined time has passed since the AC power supply and the rectifier circuit were electrically connected. , A current control gain based on the calculated amount of change in DC voltage is set, and a PW based on the set current control gain is set.
Since the switching element is PWM-controlled based on the M duty and the input current supplied by the AC power supply is feedback-controlled, deterioration of the control response in consideration of the power supply of the set environment and the impedance of the set reactor is reduced. A small and stable AC current control device can be easily realized without impairing the startup time.

According to the invention, the reference PWM duty is generated to perform PWM control on the switching element,
A PWM duty is calculated by setting a current control gain based on a time from when the switching element is subjected to the PWM control to when the DC voltage reaches a predetermined value, and the PWM control is performed on the switching element based on the PWM duty to perform feedback control. As a result, it is possible to realize a stable AC current control device with little deterioration of the control response in consideration of the power supply of the set environment and the impedance of the set reactor, and a step-up voltage exceeding a predetermined voltage value. Is not performed, the upper limit of the DC voltage is set, and overvoltage of the DC voltage can be prevented, and the operation can be performed safely.

Further, according to the present invention, the switching element is PWM-controlled by generating a reference PWM duty,
The value of the DC voltage after a predetermined time has elapsed since the PWM control of the switching element is measured, the current control gain is set based on the calculated change amount of the DC voltage, the PWM duty is calculated, and the PWM duty is calculated based on the PWM duty. Since the switching element is PWM-controlled and feedback-controlled, it is possible to realize a stable AC current control device with less deterioration in control response in consideration of the power supply of the set environment and the impedance of the set reactor, The processing time until the AC current control by the current control gain is constant, and the apparent operation is stabilized.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an AC current control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a DC voltage change when a relay 14 is turned on.

FIG. 3 is a flowchart illustrating a setting sequence of a current control gain K;

FIG. 4 is a flowchart showing another current control gain K setting sequence.

FIG. 5 is a configuration diagram example of a relay 14;

FIG. 6 is an overall configuration diagram of an AC current control device according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a change in DC voltage when the motor is operated with the reference PWM duty generated by the reference duty generation means 18;

FIG. 8 is a flowchart showing a setting sequence of a current control gain K;

FIG. 9 is a flowchart showing another current control gain K setting sequence.

FIG. 10 is an overall configuration diagram showing a configuration of a conventional AC control device.

FIG. 11 is a reactor current waveform diagram based on a difference in a value of a current control gain K.

[Explanation of symbols]

1 AC power supply, 2 diode bridge, 3 reactor, 4 converter control means, 5 smoothing capacitor, 6
Voltage control means, 7 reverse blocking diode, 8 switching element, 9 current detection means, 10 PWM means, 11
Current control means, 12 voltage phase detection means, 13 sine wave creation means, 14 relays, 15 current control gain setting means, 16 power supply impedance, 17 multiplication means.

Claims (13)

[Claims] An AC power supply for converting a voltage applied by an AC power supply to a DC voltage based on at least a current flowing through a rectifier circuit including a reactor, a diode, a smoothing capacitor, and a switching element and the converted DC voltage. PWM according to a set current control gain to feedback control the input current supplied by
An AC current control device that calculates a duty and performs PWM control on the switching element based on the PWM duty. When a switching operation is performed, a relay circuit that electrically connects the AC power supply and the rectifier circuit; Current control gain setting means for switching a circuit to electrically connect the AC power supply and the rectifier circuit, calculating the current control gain based on a change in the DC voltage, and setting the current control gain. Characteristic alternating current control device. 2. The method according to claim 1, wherein the current control gain setting means sets a time from when the AC power supply is electrically connected to the rectifier circuit by the relay circuit to when the DC voltage value reaches a predetermined voltage value. Is detected as a change in the DC voltage, wherein the current control gain is set such that a correlation between the time and the value of the current control gain is positive. AC current control device. 3. The current control gain setting means, wherein the amount of change in the value of the DC voltage from a point in time at which the AC power supply and the rectifier circuit are electrically connected by the relay circuit to a predetermined time is determined. The current control gain is calculated as a change in a DC voltage, and at this time, the current control gain is set such that a correlation between the change amount and the value of the current control gain becomes negative. AC current control device. 4. The current control gain setting means according to claim 1, wherein a phase during a half cycle of said AC power supply becomes a predetermined phase.
2. The AC current control device according to claim 1, wherein an electrical connection between the AC power supply and the rectifier circuit by the relay circuit is started. 5. The relay circuit according to claim 1, wherein the first relay means having a resistance connected in series and the second relay means having no resistance connected thereto are connected in parallel. Until the current control gain is set, the AC power supply and the rectifier circuit are electrically connected by the first relay means, and after the current control gain is set, the second relay means 2. The AC current control device according to claim 1, wherein an AC power supply is electrically connected to the rectifier circuit. 6. The AC power supply for converting a voltage applied by an AC power supply into a DC voltage based on at least a current flowing through a rectifier circuit including a reactor, a diode, a smoothing capacitor, and a switching element and the converted DC voltage. PWM according to a set current control gain to feedback control the input current supplied by
In an AC current control device for calculating a duty and performing PWM control on the switching element based on the PWM duty, reference duty generating means for generating a predetermined reference PWM duty, and reference PWM generated by the reference duty generating means An AC current control device, comprising: a current control gain setting means for calculating and setting the current control gain based on a change in the DC voltage when the switching element is driven with a duty. 7. The current control gain setting means detects, as a change in the DC voltage, a time from when the switching element is driven with the reference PWM duty to when the switching element reaches a predetermined voltage value. 7. The AC current control device according to claim 6, wherein the current control gain is set such that a correlation between the time and the value of the current control gain becomes positive. 8. The current control gain setting means calculates a change amount of the DC voltage value from a time when the switching element is driven with the reference PWM duty to a predetermined time as a change in the DC voltage. 7. The AC current control device according to claim 6, wherein the current control gain is set such that the correlation between the amount of change and the value of the current control gain is negative. 9. The current control gain setting means, when a phase during a half cycle of the AC power supply becomes a predetermined phase,
7. The AC current control device according to claim 6, wherein the driving of the switching element at the reference PWM duty is started. 10. An AC power supply, at least a reactor,
A step of electrically connecting a rectifier circuit composed of a diode, a smoothing capacitor, and a switching element, and converting a voltage applied by the AC power supply to a DC voltage, wherein the AC power supply and the rectifier circuit are electrically connected to each other. A step of measuring the time from the connection until the DC voltage reaches a predetermined value, and calculating a current control gain based on the measured time,
Setting, calculating a PWM duty based on the set current control gain, performing PWM control of the switching element based on the PWM duty, and performing feedback control of an input current supplied from the AC power supply. And a control method for an AC current control device. 11. An AC power supply, at least a reactor,
A step of electrically connecting a rectifier circuit composed of a diode, a smoothing capacitor, and a switching element, and converting a voltage applied by the AC power supply to a DC voltage, wherein the AC power supply and the rectifier circuit are electrically connected to each other. Measuring the value of the DC voltage after a predetermined time has passed since the connection, and calculating the amount of change in the DC voltage; and calculating and setting a current control gain based on the calculated amount of change in the DC voltage A step of calculating a PWM duty based on the set current control gain; and a step of performing PWM control of the switching element based on the PWM duty and performing a feedback control of an input current supplied from the AC power supply. A control method for an AC current control device, comprising: 12. An AC power supply, at least a reactor,
A step of electrically connecting a rectifier circuit including a diode, a smoothing capacitor, and a switching element to convert a voltage applied by the AC power supply to a DC voltage; and generating a reference PWM duty to switch the switching element to PWM. Controlling the input current supplied from the AC power supply, and performing feedback control on the input current supplied from the AC power supply; measuring the time from when the switching element is PWM-controlled until the DC voltage reaches a predetermined value; Calculate the current control gain based on
Setting, a step of calculating a PWM duty based on the set current control gain, and a step of performing PWM control of the switching element based on the PWM duty based on the set current control gain. A control method for an AC current control device. 13. An AC power supply, at least a reactor,
A step of electrically connecting a rectifier circuit including a diode, a smoothing capacitor, and a switching element to convert a voltage applied by the AC power supply to a DC voltage; and generating a reference PWM duty to switch the switching element to PWM. Controlling the input current supplied by the AC power supply in a feedback manner; and measuring a value of the DC voltage after a lapse of a predetermined time after performing the PWM control on the switching element to calculate a change amount of the DC voltage. Calculating and setting a current control gain based on the calculated amount of change in DC voltage; calculating a PWM duty based on the set current control gain; and setting the current control gain PWM controlling the switching element based on the PWM duty based on The method of the alternating current control device according to claim and.