TWI596876B - Power converter and controlling method thereof - Google Patents

Description

Power conversion device and control method thereof

The present invention relates to a power conversion device and a control method thereof, and more particularly to a power conversion device having an output operation range and a control method thereof.

The power conversion device mainly converts the voltage signal into an operating power source suitable for various electronic devices, loads or other powered devices. The power conversion device can generate the operating power according to the user's setting, and can also output the amplified voltage signal according to the input voltage signal.

In general, when the power converter only outputs a basic waveform, such as a sine wave, the power converter can limit the output voltage peak and the rms value according to the voltage value of the basic waveform. However, when the sine wave output from the power converter has a carrier wave or other square wave or higher harmonics, because these output signals need to analyze a large amount of data analysis, the power converter can limit the output voltage peak according to the voltage value of the output waveform. And the rms value, so the power converter needs to have better computing performance, in order to cope with the cumbersome process of detecting the output signal, so that the cost of the power converter increases. In addition, even if the power converter can limit the output voltage peak value and the root mean square value according to the voltage value of the basic waveform, the current power converter has no basis to limit the output operation range. Without limiting the output operating range, the internal components of the power converter may operate in excess conditions, increasing the chance of power converter damage.

The invention provides a power conversion device and a control method thereof, thereby solving the problem that the conventional power converter has no basis to limit the output operation range.

The power conversion device and the control method thereof disclosed by the invention have a conversion circuit, a filter circuit, a measurement circuit and a control circuit. The conversion circuit converts the voltage signal into an operation signal, and adjusts the operation voltage value and the operation frequency of the operation signal according to the control signal. The filter circuit is electrically connected to the conversion circuit to generate an operating current according to the operation signal. The measuring circuit is electrically connected to the filter circuit to measure the magnitude of the working current. The control circuit is electrically connected to the measuring circuit and the converting circuit. When the product of the operating frequency of the operating signal and the operating voltage exceeds the limit value, the control circuit adjusts the control signal according to the magnitude of the working current or controls the switching circuit to stop converting the voltage signal. The limit value is set according to the product of the operating frequency of the operation signal and the operating voltage value when the magnitude of the operating current reaches the rated current value of the filter circuit.

According to the power conversion device and the control method thereof, when the current of the filter circuit reaches the rated current value, the product of the operating voltage value of the operation signal converted by the conversion circuit and the operating frequency is used as the power conversion device. The limit value. Therefore, when the product of the operating frequency of the operation signal and the operating voltage value exceeds the limit value, the frequency and voltage value of the output signal of the conversion circuit may be adjusted, or the conversion circuit may be controlled to stop outputting the operation signal, so that the power conversion device internally The components are not over-operated, which in turn defines the output frequency range of the power converter. Moreover, regardless of whether the signal output by the power conversion device is a higher harmonic, the operating current on the filter circuit can be quickly detected, and the power conversion device does not need to analyze a large amount of data, so that the power conversion device system reduces the computational cost and costs. Reduced, you can still effectively limit the output voltage peak, rms or output frequency range.

The above description of the disclosure and the following description of the embodiments of the present invention are intended to illustrate and explain the spirit and principles of the invention, and to provide further explanation of the scope of the invention.

The detailed features and advantages of the present invention are set forth in the Detailed Description of the Detailed Description of the <RTIgt; </ RTI> <RTIgt; </ RTI> </ RTI> </ RTI> <RTIgt; The objects and advantages associated with the present invention can be readily understood by those skilled in the art. The following examples are intended to describe the present invention in further detail, but are not intended to limit the scope of the invention.

Please refer to FIG. 1. FIG. 1 is a functional block diagram of a power conversion device according to an embodiment of the invention. As shown in FIG. 1, the power conversion device 10 has a conversion circuit 11, a filter circuit 13, a measurement circuit 15, and a control circuit 17. The conversion circuit 11 converts the voltage signal into an operation signal, and adjusts the operation voltage value and the operation frequency of the operation signal according to the control signal. The voltage signal can be an AC signal or a DC signal. For convenience of illustration and description, the following embodiments and drawings The middle is represented by a DC signal, but is not intended to limit the embodiment. The filter circuit 13 is electrically connected to the conversion circuit 11, and generates an operating current according to the operation signal output from the conversion circuit 11. The measuring circuit 15 is electrically connected to the filter circuit 13 for measuring the magnitude of the operating current generated by the filter circuit 13. The control circuit 17 is electrically connected to the measuring circuit 15 and the converting circuit 11. When the product of the operating frequency of the operating signal and the operating voltage exceeds the limit value, the control circuit 17 adjusts the control signal according to the magnitude of the operating current or controls the switching circuit 11 to stop the conversion. Voltage signal.

The limit value is set according to the product of the operating frequency of the operation signal and the operating voltage value when the magnitude of the operating current reaches the rated current value of the filter circuit 13. The rated current value of the filter circuit 13 is, for example, a maximum current value operable on the filter circuit 13, a maximum current value for safe operation of the filter circuit 13, or other rated value associated with the filter circuit 13. The maximum current value of the safe operation of the filter circuit 13 is, for example, the maximum current value at which the filter circuit 13 can operate, and the derated current value, such as 90%, 80%, 75% or other derating standard of the operable maximum current value. In other embodiments, the limit value may also be set according to the product of the operating frequency of the operation signal and the operating voltage value when the current value on one of the components of the filter circuit 13 reaches the rated current value. It should be understood by those of ordinary skill in the art that the operating current of the filter circuit 13 reaches the rated current, and it can also be considered that the operating power of the filter circuit 13 reaches the rated power or the operating voltage of the filter circuit 13 reaches the rated voltage value.

Next, please refer to FIG. 2. FIG. 2 is a schematic circuit diagram of a power conversion device according to another embodiment of the present invention. As shown in FIG. 2, the power conversion device 20 has a conversion circuit 21, a filter circuit 23, a measurement circuit 25, and a control circuit 27. The conversion circuit 21 is, for example, a bridge converter, a DC to AC converter, a DC to DC converter or other suitable converter. In one embodiment, the conversion circuit 21 has a first switch M1, a second switch M2, a third switch M3, and a fourth switch M4. The first switch M1 and the second switch M2 are connected in series to form a first series branch, and the third switch M3 and the fourth switch M4 are connected in series to form a second series branch, and the first series branch and the second series branch are connected in parallel to form Conversion circuit 21. The first series branch and the second series branch are electrically connected to both ends of the power source 30 respectively to receive the voltage signal output by the power source 30.

The filter circuit 23 is, for example, an LC filter, an inductive filter, an RC filter, a π-type filter, or other suitable filter. In the LC filter, the filter circuit 23 has a series inductor L1, an inductor L2, a resistor R and a capacitor C. The two ends of the filter circuit 23 are electrically connected between the first switch M1 and the second switch M2, respectively. Between the switch M3 and the fourth switch M4, the operation signal generated by the conversion circuit 21 for converting the voltage signal is received.

The operation signal has an operating voltage value and an operating frequency. In one embodiment, the first switch M1, the second switch M2, the third switch M3, and the fourth switch M4 of the conversion circuit 21 are respectively controlled according to the control signal XA, the control signal XB, and the control signal The signal XC and the control signal XD are sequentially switched on and off, and the operating voltage value and operating frequency of the operation signal are adjusted accordingly. The filter circuit 23 receives the operation signal generated by the conversion circuit 21 and filters the operation signal to provide the filtered operation signal to the load 40. When the filter circuit 23 filters the operation signal, the current flowing through the capacitor C and the resistor R is the operating current Ic.

The measuring circuit 25 is electrically connected to both ends of the resistor R for measuring the voltage difference across the resistor R. The measuring circuit 25 calculates the magnitude of the operating current Ic based on the voltage difference across the resistor R and the resistance value of the resistor R. The control circuit 27 is electrically connected to the measuring circuit 25 and the conversion circuit 21 to obtain the magnitude of the operating current Ic measured by the measuring circuit 25, and when the product of the operating frequency of the operating signal and the operating voltage exceeds the limit value, The magnitude of the current Ic adjusts the control signal or controls the conversion circuit 21 to stop converting the voltage signal.

In one embodiment, the product of the operating frequency of the operational signal and the operating voltage value is associated with the magnitude of the operating current Ic. Looking at the resistance R and the capacitance C of the filter circuit 23, the operating voltage value of the operation signal is substantially equal to . When the operating voltage value of the operation signal does not change and the operating frequency of the operation signal increases, the operating current Ic flowing through the resistor R increases. When the operating frequency of the operation signal is constant, and the operating voltage value of the operation signal is larger, the operating current Ic flowing through the resistor R is also larger. Therefore, by limiting the product of the operating frequency of the operation signal and the operating voltage value, the operating current Ic on the filter circuit 23 can be prevented from being excessively large, thereby preventing the component over-operation on the filter circuit 23.

In other words, the rated current, rated voltage or rated power of the filter circuit 23 can define the output operating range of the power converter 10, that is, the product of the operating frequency of the operating signal and the operating voltage value. For example, the control circuit 27 controls the operating voltage value of the output signal of the conversion circuit 21 to be at a preset voltage value, and adjusts the operating frequency of the operation signal. The filter circuit 23 generates an operating current Ic based on the operation signal of the adjusted operating frequency. When the equivalent measuring circuit 25 measures that the operating current Ic of the filter circuit 23 reaches the rated current value, the control circuit 27 takes the product of the preset voltage value and the operating frequency as a limit value. Therefore, when the product of the operating frequency of the operation signal and the current operating voltage value exceeds the limit value, the control circuit 27 can adjust the control signal according to the magnitude of the operating current Ic or control the conversion circuit 21 to stop converting the voltage signal.

In a practical example, the resistance of the resistor R on the filter circuit 23 is, for example, 6 ohms, and the maximum operating power is, for example, 100 watts. The maximum operating power of the resistor R is, for example, 75 watts after derating. According to the resistance value of the resistor R and the operating power of 75 watts after the standard, the standard operating voltage of the resistor R is 21.21V ( ). The control circuit 27 controls the conversion circuit 11 to output an operation signal having an operation voltage value of 500V, and adjusts the operation frequency of the operation signal until the measurement circuit 25 measures the voltage difference between the two ends of the resistor R to be 21.21V, and obtains the operation signal at that time. The operating frequency is, for example, 160 Hz. The control circuit 27 takes the product of the voltage value 500V and the operating frequency of 160 Hz as a limit value. Thereafter, when the product of the operating voltage value of the operation signal outputted by the conversion circuit 21 and the operating frequency exceeds 80000, the control circuit 27 adjusts the generated control signal or controls the conversion circuit 21 to stop the switching of the voltage signal.

In another example, the control circuit 27 can also control the operating frequency of the output signal of the conversion circuit 21 to be at a preset frequency, and adjust the operating voltage value of the operation signal. The filter circuit 23 generates an operating current Ic based on the operation signal of the adjusted operating voltage value. When the equivalent measuring circuit 25 measures that the operating current Ic of the filter circuit 23 reaches the rated current value, the control circuit 27 uses the product of the preset frequency and the current operating voltage value as the limit value.

When the product of the operating frequency of the operation signal and the operating voltage value exceeds the limit value, the control circuit 17 can control the switching circuit 21 to stop the switching of the voltage signal, and even if the switching circuit 11 stops outputting the operation signal. The control circuit 27 can also adjust the control signal according to the magnitude of the operating current Ic. In the foregoing example, when the operating voltage of the operating signal is substantially equal to The control circuit 27 can obtain the proportional relationship between the operating voltage value and the operating frequency according to the magnitude of the operating current Ic, and adjust the output control signal according to the limiting value and the proportional relationship, so that the converting circuit 21 can be based on the adjusted control signal. The converted voltage signal is an operation signal.

In the embodiment of FIG. 2, the measuring circuit 25 is electrically connected to both ends of the resistor R, and the magnitude of the operating current Ic is calculated according to the voltage difference between the resistors R. In practice, the measurement circuit 25 can also be a Hall sensor or a Current Shunt Resistance. The Hall sensor senses the operating current Ic through the resistor R by electromagnetic induction. The current detecting resistor is connected in series with the resistor R, and the operating current Ic is calculated by the voltage on the current detecting resistor. In another example, the measurement circuit 25 can also pass through the sense of Hall. A detector or current sense resistor measures the current through inductor L1 and the current through load 40, and the magnitude of operating current Ic is calculated via the current through inductor L1 and the current through load 40. The method of designing the measurement circuit 15 to obtain the operating current Ic according to the actual situation is not limited in this embodiment.

For a more detailed description of the control method of the power conversion device, please refer to FIG. 1 and FIG. 3 together. FIG. 3 is a flow chart showing the steps of the control method according to an embodiment of the invention. As shown in FIG. 3, in step S501, the conversion circuit 11 converts the voltage signal into an operation signal. The operation signal has an operating voltage value and an operating frequency. In step S502, the conversion circuit 11 adjusts the operating voltage value and the operating frequency of the operation signal according to the control signal output from the control circuit 17. In step S503, the operation signal generates an operating current via the filter circuit 13. In step S504, the measuring circuit 15 measures the magnitude of the operating current on the filter circuit 13. In step S505, when the product of the operating frequency of the operation signal and the operating voltage value exceeds the limit value, the control circuit 17 adjusts the control signal according to the magnitude of the operating current or controls the conversion circuit 11 to stop converting the voltage signal into a voltage signal.

The limit value of the product of the operating frequency and the operating voltage value is set, for example, when the magnitude of the operating current reaches the rated current value of the filter circuit 13, based on the product of the operating frequency of the operating signal and the operating voltage value. The control method of the power conversion device according to the present invention has been substantially disclosed in the above-described embodiments, and the description of the embodiment will not be repeated here.

In summary, the embodiments of the present invention provide a power conversion device and a control method thereof, which define an output operation range of a power conversion device by a rated current, a rated voltage, or a rated power of the filter circuit. That is to say, when the current of the filter circuit reaches the rated current value, the product of the operating voltage value and the operating frequency of the operating signal at the time is used as a basis for the control circuit to adjust the control signal. Then, when the conversion circuit generates an operation signal generated by the control signal, and the product of the operation frequency and the operation voltage value exceeds the limit value, the control circuit adjusts the control signal to adjust the operation signal outputted by the conversion circuit or directly controls the conversion circuit to stop outputting. The operation signal makes the components inside the power conversion device not excessively operated, and defines the output operation range of the power converter.

Although the present invention has been disclosed above in the foregoing embodiments, it is not intended to limit the invention. It is within the scope of the invention to be modified and modified without departing from the spirit and scope of the invention. Please refer to the attached patent application for the scope of protection defined by the present invention.

10, 20‧‧‧ power conversion device

11, 21‧‧‧ conversion circuit

13, 23‧‧‧ Filter circuit

15, 25‧‧‧Measurement circuit

17, 27‧‧‧ Control circuit

30‧‧‧Power supply

40‧‧‧ load

M1‧‧‧ first switch

M2‧‧‧ second switch

M3‧‧‧ third switch

M4‧‧‧fourth switch

XA ~ XD‧‧‧ control signal

L1, L2‧‧‧ inductance

R‧‧‧resistance

C‧‧‧ capacitor

1 is a functional block diagram of a power conversion device according to an embodiment of the invention. 2 is a circuit diagram of a power conversion device according to another embodiment of the present invention. FIG. 3 is a flow chart showing the steps of a control method according to an embodiment of the invention.

10‧‧‧Power conversion device

11‧‧‧Transition circuit

13‧‧‧Filter circuit

15‧‧‧Measurement circuit

17‧‧‧Control circuit

Claims (10)

A power conversion device includes: a conversion circuit that converts a voltage signal into an operation signal, and adjusts an operation voltage value and an operation frequency of the operation signal according to a control signal; and a filter circuit electrically connected to the conversion circuit, Generating an operating current according to the operation signal; a measuring circuit electrically connected to the filtering circuit for measuring the working current; and a control circuit electrically connecting the measuring circuit and the converting circuit when the When the product of the operating frequency of the operation signal and the operating voltage value exceeds a limit value, the control circuit adjusts the control signal according to the magnitude of the operating current or controls the conversion circuit to stop converting the voltage signal; wherein the limit value is When the magnitude of the operating current reaches the rated current value of the filter circuit, it is set according to the product of the operating frequency of the operation signal and the operating voltage value. The power conversion device of claim 1, wherein when the control circuit controls the operating voltage value of the operation signal to be at a predetermined voltage value, and adjusting the operating frequency of the operation signal, the magnitude of the operating current reaches the When the rated current value of the filter circuit is used, the product of the preset voltage value and the operating frequency is the limit value. The power conversion device of claim 1, wherein when the control circuit controls the operating frequency of the operation signal to be at a predetermined frequency, and adjusting the operating voltage value of the operation signal, the working current reaches the filtering. When the rated current value of the circuit is used, the product of the preset frequency and the operating voltage value is the limit value. The power conversion device of claim 1, wherein the filter circuit has a resistor, the measurement circuit is electrically connected to both ends of the resistor, and the magnitude of the operating current is calculated according to a voltage difference across the resistor. The rated current value of the filter circuit is related to the current range in which the resistor can operate. The power conversion device of claim 1, wherein when the product of the operating frequency of the operation signal and the operating voltage value exceeds the limit value, the control circuit determines the operating frequency and the operation according to the magnitude of the operating current. A proportional relationship of the voltage values, and adjusting the control signal according to the limit value and the proportional relationship. A control method for a power conversion device includes: converting a voltage signal into an operation signal; adjusting an operation voltage value of the operation signal and an operation frequency according to a control signal; and generating an operating current through a filter circuit; Measuring the magnitude of the operating current; and when the product of the operating frequency of the operating signal and the operating voltage value exceeds a limit value, adjusting the control signal according to the magnitude of the operating current or stopping converting the voltage signal into the voltage signal The limit value is set according to the product of the operating frequency of the operation signal and the operating voltage value when the magnitude of the operating current reaches the rated current value of the filter circuit. The control method of the power conversion device of claim 6, further comprising setting the operating voltage value of the operation signal to a preset voltage value, adjusting the operating frequency of the operation signal, and causing the working current to reach the filtering. The rated current value of the circuit is set according to the product of the preset voltage value and the operating frequency. The control method of the power conversion device of claim 6, further comprising setting the operating frequency of the operation signal to a predetermined frequency, adjusting the operating voltage value of the operating signal, and causing the working current to reach the filtering circuit. The rated current value is set according to the product of the preset frequency and the operating voltage value. The control method of the power conversion device of claim 6, wherein the filter circuit has a resistor, and in the step of measuring the magnitude of the operating current, the voltage difference between the two ends of the resistor is measured, according to the two ends of the resistor The voltage difference is calculated by calculating the magnitude of the operating current, wherein the rated current value of the filter circuit is associated with a current range operable by the resistor. The control method of the power conversion device of claim 6, wherein the step of adjusting the control signal according to the magnitude of the operating current comprises determining a ratio of the operating frequency to the operating voltage value according to the magnitude of the operating current Relationship, and adjust the control signal according to the limit value and the proportional relationship.