CN219227431U - Frequency converter and electric equipment - Google Patents

Abstract

The utility model discloses a frequency converter and electric equipment. The frequency converter comprises a rectifying circuit, a boost circuit and an inverter circuit, wherein the boost circuit is connected with the inverter circuit through a direct current bus, the output end of the inverter circuit is connected with a motor, and the frequency converter further comprises: the detection module is used for acquiring back electromotive force generated when the motor operates; the operation module is used for determining a given value of the DC bus voltage according to the back electromotive force; the control module is used for controlling the duty ratio and the switching frequency of a power switching tube in the boost circuit according to the given value of the DC bus voltage, the actual value of the DC bus voltage, the DC bus current value and the input voltage value of the boost circuit, so as to control the actual value of the DC bus voltage. The utility model can avoid the excessively high duty ratio and switching frequency of the power switching tube in the circuit, and further control the temperature rise of the power switching tube, thereby improving the working reliability of the power switching tube and prolonging the service life of the power switching tube.

Description

Frequency converter and electric equipment

Technical Field

The utility model relates to the technical field of electronic power, in particular to a frequency converter and electric equipment.

Background

At present, a large number of electric equipment (such as household and commercial air-conditioning products) are in large-area frequency conversion, the reliability of a frequency conversion driving technology is increasingly focused, the temperature rise of a power device in a boost circuit of a frequency converter is easily too high, and the reliability and the service life of the power device are directly influenced.

Aiming at the problems that the power device in the boost circuit of the frequency converter is easy to generate too high temperature rise and directly affects the reliability and the service life of the power device in the prior art, no effective solution is proposed at present.

Disclosure of Invention

The embodiment of the utility model provides a frequency converter and electric equipment, which are used for solving the problems that the reliability and the service life of a power device are directly influenced due to the fact that the temperature rise of the power device in a boost circuit of the frequency converter is too high in the prior art.

In order to solve the technical problem, the utility model provides a frequency converter, which comprises a rectifying circuit, a boost circuit and an inverter circuit, wherein the boost circuit is connected with the inverter circuit through a direct current bus, the output end of the inverter circuit is connected with a motor, and the frequency converter further comprises:

the detection module is used for acquiring back electromotive force generated when the motor runs;

the operation module is used for determining a given value of the direct current bus voltage according to the counter electromotive force;

the control module is used for controlling the duty ratio and the switching frequency of a power switch tube in the boost circuit according to the given value of the DC bus voltage, the actual value of the DC bus voltage, the DC bus current value and the input voltage value of the boost circuit, so as to control the actual value of the DC bus voltage.

Further, the control module includes:

the inverting input end of the first comparator is used for inputting the actual value of the direct current bus voltage, the non-inverting input end of the first comparator is used for inputting the given value of the direct current bus voltage, the output end of the first comparator outputs a high-low level signal, and the high-low level signal is subjected to PI control to obtain a reference current value;

the multiplication device is used for carrying out multiplication on the input voltage value of the boost circuit and the reference current value to obtain a reference current value tracking the input voltage phase of the boost circuit;

and the second comparator is used for inputting the direct current bus current value by an input end in an inverted mode, inputting the reference current value of the input voltage phase of the tracking boost circuit by an in-phase input end, and outputting a PWM signal by an output end so as to control the duty ratio and the switching frequency of a power switching tube in the boost circuit.

The utility model also provides electric equipment, which comprises a motor and the frequency converter.

By applying the technical scheme of the utility model, the given value of the DC bus voltage is determined by the counter electromotive force generated during the operation of the motor, and then the duty ratio and the switching frequency of the power switching tube in the circuit are controlled according to the given value of the DC bus voltage, the actual value of the DC bus voltage, the DC bus current value and the input voltage value of the circuit, so that the actual value of the DC bus voltage is controlled, the over-high duty ratio and the switching frequency of the power switching tube in the circuit can be avoided, and the temperature rise of the power switching tube is further controlled, thereby improving the working reliability of the power switching tube and prolonging the service life of the power switching tube.

Drawings

Fig. 1 is a block diagram of a frequency converter according to an embodiment of the present utility model.

Detailed Description

In order to make the objects, technical solutions and advantages of the present utility model more apparent, the present utility model will be described in further detail below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

The terminology used in the embodiments of the utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, the "plurality" generally includes at least two.

It should be understood that the term "and/or" as used herein is merely one relationship describing the association of the associated objects, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

It should be understood that although the terms first, second, etc. may be used in embodiments of the present utility model to describe comparators, these comparators should not be limited by these terms. These terms are only used to distinguish comparators disposed at different locations. For example, a first comparator may also be referred to as a second comparator, and similarly, a second comparator may also be referred to as a first comparator, without departing from the scope of embodiments of the present utility model.

The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrase "if determined" or "if detected (stated condition or event)" may be interpreted as "when determined" or "in response to determination" or "when detected (stated condition or event)" or "in response to detection (stated condition or event), depending on the context.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a product or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such product or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a commodity or device comprising such element.

Alternative embodiments of the present utility model will be described in detail below with reference to the accompanying drawings.

Example 1

With the increasing market competition of frequency conversion electric equipment, the design requirements of various manufacturers on the air conditioner frequency converter are gradually improved, and particularly, the properties of the frequency converter, such as functions, reliability and durability, of the frequency converter, which are directly related to the use experience of customers, are more focused by frequency converter developers.

In order to solve the harmonic influence of a unit on a power grid, the existing frequency converter generally carries out active filtering through a boost circuit, and in order to reduce the product cost as much as possible, a power device in the boost circuit generally works at a very high switching frequency (20 KHz or more), and the temperature rise of the power device can be maintained at a relatively high working temperature because the power device itself bears running current, so that the working reliability and the service life of the power device can be influenced for a long time.

In order to solve the above-mentioned problem, the present embodiment provides a frequency converter, as shown in fig. 1 provided above, the frequency converter includes a rectifying circuit 1, a boost circuit 2, and an inverter circuit 3, the boost circuit 2 and the inverter circuit 3 are connected through a dc bus, an output end of the inverter circuit 3 is connected to a motor M1, the frequency converter further includes: the detection module 4 is used for acquiring back electromotive force generated when the motor operates; an operation module 5, configured to determine a given value Vref of a dc bus voltage according to the back electromotive force; the control module 6 is used for controlling the duty ratio and the switching frequency of a power switch tube in the boost circuit according to the given value Vref of the DC bus voltage, the actual value Vout of the DC bus voltage, the DC bus current value and the input voltage value Vin of the boost circuit, and further controlling the actual value Vout of the DC bus voltage.

According to the frequency converter, the given value Vref of the direct current bus voltage is determined through the counter electromotive force generated during motor operation, and then the duty ratio and the switching frequency of the power switching tube in the boost circuit are controlled according to the given value Vref of the direct current bus voltage, the actual value Vout of the direct current bus voltage, the direct current bus current value and the input voltage value Vin of the boost circuit, and then the actual value Vout of the direct current bus voltage is controlled, so that the duty ratio and the switching frequency of the power switching tube in the boost circuit can be prevented from being too high, and the temperature rise of the power switching tube is further controlled, so that the working reliability of the power switching tube is improved, and the service life of the power switching tube is prolonged.

As shown in fig. 1 mentioned above, the control module 6 includes: the output end of the first comparator A1 outputs a high level 1 when the given value Vref of the DC bus voltage is larger than the actual value Vout of the DC bus voltage, and outputs a low level 0 when the given value Vref of the DC bus voltage is smaller than the actual value Vout of the DC bus voltage, and the high level signal and the low level signal are subjected to PI control to obtain a reference current value Iref0.

The multiplication unit M obtains a reference current value tracking the input voltage phase of the boost circuit through the multiplication unit, and multiplies the input voltage Vin of the boost circuit and the reference current value Iref0 through the multiplication unit to obtain the reference current value Iref tracking the input voltage phase of the boost circuit.

The second comparator A2 outputs a PWM signal through the second comparator, the inverting input end of the second comparator inputs a DC bus current value acquired by the current sensor, the non-inverting input end is used for inputting a reference current value Iref for tracking the input voltage phase of the boost circuit, the output end is used for outputting the PWM signal, and when the reference current value is larger than the DC bus current value, a high-level signal is output; when the reference current value is smaller than the direct current bus current value, a low-level signal is output to control the duty ratio and the switching frequency of the power switching tubes S1 and S2 in the boost circuit.

Example 2

The embodiment provides electric equipment, which comprises a motor and further comprises the frequency converter, wherein the frequency converter is used for avoiding overhigh duty ratio and switching frequency of a power switch tube in a boost circuit and further controlling temperature rise of the power switch tube, so that the working reliability of the power switch tube is improved, and the service life of the power switch tube is prolonged.

The frequency converter embodiments described above are merely illustrative, wherein the modules illustrated as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules, i.e. may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present utility model, and are not limiting; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model.

Claims (3)

1. The utility model provides a frequency converter, the frequency converter includes rectifier circuit, boost circuit and inverter circuit, connects through direct current busbar between boost circuit and the inverter circuit, the motor is connected to inverter circuit's output, its characterized in that, the frequency converter still includes:

the detection module is used for acquiring back electromotive force generated when the motor runs;

the operation module is used for determining a given value of the direct current bus voltage according to the counter electromotive force;

the control module is used for controlling the duty ratio and the switching frequency of a power switch tube in the boost circuit according to the given value of the DC bus voltage, the actual value of the DC bus voltage, the DC bus current value and the input voltage value of the boost circuit, so as to control the actual value of the DC bus voltage.

2. The frequency converter of claim 1, wherein the control module comprises:

the inverting input end of the first comparator is used for inputting the actual value of the direct current bus voltage, the non-inverting input end of the first comparator is used for inputting the given value of the direct current bus voltage, the output end of the first comparator outputs a high-low level signal, and the high-low level signal is subjected to PI control to obtain a reference current value;

the multiplication device is used for carrying out multiplication on the input voltage value of the boost circuit and the reference current value to obtain a reference current value tracking the input voltage phase of the boost circuit;

and the second comparator is used for inputting the direct current bus current value by an input end in an inverted mode, inputting the reference current value of the input voltage phase of the tracking boost circuit by an in-phase input end, and outputting a PWM signal by an output end so as to control the duty ratio and the switching frequency of a power switching tube in the boost circuit.

3. A powered device comprising a motor, further comprising the frequency converter of claim 1 or 2.

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