RU92260U1 - BRIDGE INVERTER WITH TRANSFORMER PROTECTION FROM ONE-SIDED SATURATION - Google Patents

Abstract

A bridge inverter with protection of the transformer from one-sided saturation, comprising a bridge switch for converting direct voltage to alternating current, having first and second control inputs, used to control the closure and opening of the switching elements of the bridge switch when generating the output voltages of the first and second half-cycles; output transformer, the primary winding of which is connected to the output of the bridge switch; a clock that sets the period of the output voltage with a duration of the generated output pulses equal to half the period, and having first and second outputs with a shift of the output pulses of the second output by half the period relative to the pulses at the first output; the first voltage generating channel of the first half-cycle with the value of the effective voltage value set for it; a second voltage generation channel of the second half-cycle with an average voltage value equal to the average voltage value of the first half-cycle; means for detecting a measuring voltage proportional to the magnetizing EMF of the magnetic circuit of the output transformer in the first and second half-periods, connected by an output to the inputs of the first and second channels of voltage generation of the first and second half-periods, characterized in that the first control input of the bridge switch is connected to the first via a normally closed electronic key clock output; the second control input of the bridge switch through the second normally closed electronic key is connected to the second output of the clock generator; control input

Description

This technical solution relates to the field of electrical engineering and is intended for use in DC-AC converters.

Inverters are known for converting dc voltage to ac with preventing one-sided saturation of the output transformer and with the separate formation of the first and second half-cycles [1], [2]. They have a drawback - separate functional control circuits for both closing and opening the bridge switch keys with signals coming from the clock generator and half-period drivers are part of the output functional node circuit with a bridge switch, and therefore contain an overestimated number of interstage connections, which complicates the design.

The closest known analogue is the patent of the Russian Federation [3], which describes the inverter device. The voltage inverter with the prevention of one-sided saturation of the transformer [3] is made as follows.

It contains a DC-to-AC converter, to the control inputs of which the outputs of the clock generator and two channels for forming the first and second half-periods of voltage are connected. An output transformer is connected to the output of the DC / AC converter. The clock generator that sets the output voltage period has two outputs with a shift of the output pulses of the second output by half the period relative to the pulses at the first output. Also contains means to stabilize the current value of the output voltage and prevent one-sided saturation of the output transformer.

The disadvantage of this voltage inverter with the prevention of one-sided saturation of the transformer is as follows.

A functional unit is a DC-to-AC converter, in addition to performing the main function, i.e. switching high currents, includes means for separately controlling the on and off control of power switching elements, for example, keys of a bridge switch. Therefore, it contains an overestimated amount of control input pins and communication circuits with half-period formers. Since control circuits are built into the high-current cooled unit and the number of communication lines with the other shaper circuits is accordingly increased, the design is complicated, the overall dimensions of the design are deteriorated.

The problem to which the claimed technical solution is directed is to simplify the design.

For this, a modified control circuit for the power switching elements of the DC / AC converter, made with a bridge switch, was applied, which made it possible to reduce the number of communication lines between the power part and the control circuits.

The proposed solution is a bridge inverter with transformer protection from one-sided saturation, made as follows.

A bridge inverter with transformer protection against one-sided saturation contains the following well-known technical solutions.

A bridge switch for converting DC voltage to AC, having first and second control inputs, used to control the closure and opening of the switching elements of the bridge switch when generating the output voltages of the first second half-cycles.

The output transformer, the primary winding of which is connected to the output of the bridge switch.

A clock that sets the period of the output voltage, with a duration of the generated output pulses equal to half the period, and having first and second outputs with a shift of the output pulses of the second output by half the period relative to the pulses at the first output.

The first voltage generation channel of the first half-cycle with the value of the effective voltage value set for it.

The second voltage generation channel of the second half-cycle with an average voltage value equal to the average voltage value of the first half-cycle.

Means of controlling the degree of magnetic saturation of the magnetic core of the output transformer, connected by the output to the inputs of the first and second channels of voltage formation of the first and second half-periods.

The signs that distinguish the proposed solution from the known, the following.

The first control input of the bridge switch through the first normally closed electronic key is connected to the first output of the clock generator.

The second control input of the bridge switch through the second normally closed electronic key is connected to the second output of the clock generator.

The control input of the first electronic key is connected to the output of the first voltage generating channel of the first half-cycle.

The control input of the second electronic key is connected to the output of the second voltage generating channel of the second half-cycle.

The circuit of a bridge inverter with transformer protection from one-sided saturation is shown in FIG. 1, where the following designations of the elements and assemblies of which the bridge inverter is made are adopted.

1, 2 - input;

3, 4 - output;

5 - bridge switch;

6 - output transformer;

7 - primary winding;

8 - output winding;

9 - winding measuring the EMF magnetization;

10 - means for detecting the measuring voltage proportional to the EMF magnetization of the magnetic circuit of the output transformer in the first and second half-periods;

11 is a clock pulse generator that sets the period of the output voltage;

12 - the first channel of voltage formation of the first half-cycle;

13 - the second channel of the voltage formation of the second half-cycle;

14 - calculator of the effective voltage value of the first half-cycle;

15 - calculator of the average voltage value of the first half-cycle;

16 - calculator of the average voltage value of the second half-cycle;

17 - storage device;

18 is a comparator comparing the current average voltage of the second half-cycle with the average voltage value of the first half-cycle.

19 - the first normally closed electronic key;

20 - the second normally closed electronic key.

A bridge inverter with transformer protection against one-sided saturation is made as follows.

In the inverter circuit of Fig. 1, input terminals 1, 2 are intended for supplying a constant voltage to the inverter from a power source, and output terminals 3, 4 are intended for connection to a load inverter. The pins 1, 2 are connected bridge switch 5 for converting DC voltage to AC, having the first and second control inputs, used to control the closure and opening of the switching elements of the bridge switch when generating the output voltages of the first second half-cycles.

The output transformer 6 is connected by the primary winding 7 to the output of the bridge switch 5. The output transformer 6 contains an output winding 8 connected to the terminals 1, 2, and a measuring winding 9, which is used as a sensor in detecting a voltage proportional to the EMF of the magnetization of the transformer magnetic circuit. The output winding 8 of the transformer 6 is connected to the output terminals 3, 4 for connecting the load. The output terminals 3, 4 of the bridge inverter are designed to supply an external load with an alternating voltage, stabilized by the value of the effective value with a given error, and in the range from minimum to maximum value.

To the measuring winding 9 is connected a means 10 for detecting a voltage proportional to the EMF magnetization of the magnetic circuit of the output transformer 6; this means 10 has an output for a voltage proportional to that generated in the first and second half-cycles. The clock generator 11 sets the period of the output voltage; the duration of the generated output pulses is equal to half the period. The clock generator 11 has first and second outputs, with a shift of the output pulses of the second output by half the period relative to the pulses at the first output.

To control the launch of the bridge switch 5 at the beginning of the formation of each half-cycle, electrical connections were introduced to transmit the triggering pulses from the outputs of the clock generator 11: to the first control input of the bridge switch 5 from the first output of the clock generator 11 (for the first half-cycle), and to the second control input of the bridge switch 5 - s from the second output of the clock generator 11 (for the second half-cycle).

The first channel 12 of the voltage generation of the first half-cycle with a value of the effective voltage value set for it, and the second channel 13 of the voltage generation of the second half-cycle with an average voltage equal to the average voltage of the first half-cycle, the inputs are connected to the output of the means for detecting the measuring voltage proportional to the magnetization EMF of the output magnetic circuit transformer in the first and second half-periods.

The first voltage generation channel 12 of the first half-cycle contains a calculator 14 of the effective voltage value of the first half-cycle and a calculator 15 of the average voltage value of the first half-cycle.

The second voltage generating channel 13 of the second half-cycle contains a calculator 16 of the average voltage value of the second half-cycle, a storage device 17, and a comparator 18 comparing the current average voltage of the second half-cycle with the average voltage of the first half-cycle.

The inputs of both channels 12 and 13 are connected to the output of the means 10 for detecting the voltage proportional to the EMF magnetization of the magnetic core of the transformer 6.

The first control input of the bridge switch 5 through the first normally closed electronic key 19 is connected to the first output of the clock generator 11.

The second control input of the bridge switch 5 through the second normally closed electronic key 20 is connected to the second output of the clock generator 11.

The control input of the first normally closed electronic key 19 is connected to the output of the first channel 12 for generating voltage of the first half-cycle, i.e. with the output of the calculator 14 of the effective voltage value of the first half-cycle.

The control input of the second normally closed electronic switch 20 is connected to the output of the second voltage generating channel 13 of the second half-cycle, i.e. with the output of the comparator 18.

The output of the calculator 14 of the effective voltage value is connected to the control input of the first normally closed switch 19.

The calculator 15 of the average voltage value of the first half-cycle is connected by a measuring input to the output of the means 10 for detecting the voltage proportional to the magnetization EMF of the magnetic circuit of the output transformer 6. The output of the calculator 15 for calculating the average voltage of the first half-cycle is connected to the input of the memory 17, which stores the average value of the voltage generated in the first half-cycle

The calculator 16 of the average voltage value of the second half-cycle generated in the primary winding 7 is connected by a measuring input to the output of the means 10 for detecting the voltage proportional to the magnetization EMF of the magnetic core of the transformer 6. The output of the calculator 16 of the average voltage of the second half-cycle is connected to the first voltage comparison input of the comparator 18 comparing the current average voltage of the second half-cycle with an average voltage value of the first half-cycle stored in the storage device 17.

The second voltage comparison input of the comparator 18 is connected to the output of the storage device 17, which stores the average voltage value generated in the first half-cycle.

The output of the comparator 18 is connected to the control input of a normally closed key 20.

The circuit of figure 1 works as follows.

At the inputs 1, 2 from the power source of the inverter serves a constant voltage.

From outputs 3, 4, an alternating voltage stabilized by the value of the effective value with a given error, i.e., lying in the range from minimum to maximum, is removed to the inverter load.

The DC voltage supplied to the inputs 1, 2 from the power source, the bridge switch 5 converts into alternating voltage with a predetermined period. Alternating voltage from the output of the bridge switch 5 is supplied to the output transformer 6 through the primary winding 7.

The output winding 8 of the transformer 6 is connected to the output terminals 3, 4 of the inverter, through which the voltage generated by the inverter is supplied to the load.

From the winding 9 of the measurement of the electromotive force EMF signals are taken to measure the current value of the voltage proportional to the EMF magnetization of the transformer core.

Connected to the winding 9 means 10 for detecting the measuring voltage proportional to the EMF of magnetization of the transformer magnetic circuit in the first and second half-periods, contains the load resistance of the winding 9, a rectifier of the first and second half-periods of the generated voltage, and a matching amplifier. The means 10 for detecting the measuring voltage proportional to the magnetizing EMF of the transformer magnetic circuit in the first and second half-periods has one common output on both channels 12 and 13. From this output, the measuring voltage is constantly supplied to the input circuits of channels 12 and 13, intended for measuring current voltage values and calculations calculators 13, 14 and 15. According to the results of these calculations, the separate formation of voltages in the first and second half-periods in the bridge switch 5 is controlled by opening at the right time of the corresponding normally closed electronic key 19 or 20.

The period of the output voltage of the inverter is set by the clock generator 11 of the periodic pulses, and the output signals generated by it control the bridge switch 5. The duration of the output pulses at both outputs of the clock generator 11 is equal to half a period. In special cases of execution, the duration of the output pulses at both outputs of the clock generator 11 may be somewhat different from a half-period, but practically equal to half a period if the output signal of the clock generator 11 is not a meander. The voltage generation of the first half-cycle begins with the arrival of a pulse from the first output of the clock generator 11 through the first normally closed electronic switch 19 to the first input of the bridge switch 5. In this case, the current from the power source flows through the bridge switch 5 and the primary winding 7 of the output transformer 6, and to the output winding 8 appears the generated voltage of the first half-cycle.

The voltage generation of the first half-cycle is completed upon receipt of a control signal from the output of channel 12, i.e. from the output of the calculator 14, to the control input of the first normally closed electronic key 19. The key 19 opens and the switching elements of the bridge switch 5 open. The current flow from the power source through the bridge switch 5 and the primary winding 7 of the output transformer 6 is stopped, and the first half-cycle is completed voltage at the output winding 8.

The voltage generation of the second half-cycle begins with a pulse from the second output of the clock generator 11 through the second normally closed electronic switch 20 to the second input of the bridge switch 5. In this case, the current from the power source flows through the bridge switch 5 and the primary winding 7 of the output transformer 6, and to the output winding 8 appears the generated voltage of the second half-cycle.

The voltage generation of the second half-cycle is completed when a control signal is received from the output of channel 13, i.e. from the output of the comparator 18, to the control input of the second normally closed electronic key 20. The key 20 opens, and the switching elements of the bridge switch 5 open. This stops the current flowing from the power source through the bridge switch 5 and the primary winding 7 of the output transformer 6, and the second half period of voltage at the output winding 8.

With the beginning of the formation of voltages of the first and second half-periods, a current flows through the transformer winding 7.

At the same time, signals are measured from the measuring winding 9 for measuring the current value of the voltage proportional to the magnetizing EMF of the transformer core, which are fed to the input of the measuring voltage shaper 10, which is proportional to the magnetizing EMF of the transformer magnetic circuit in the first and second half-periods.

From the output of circuit 10, the output signals are fed to channels 12 and 13, in which computational operations are carried out and the necessary pulse duration of the first and second half-periods is formed.

The output signals during the first half-cycle from the output of the means 10 for detecting the measuring voltage, which is proportional to the magnetization EMF of the magnetic circuit of the output transformer, are fed to channel 12, which contains two computing means - 14 and 15 for calculating the parameters of the current voltage generated in the first half-cycle:

- to the measuring input of the calculator 14 of the current voltage value of the first half-cycle,

- to the measuring input of the calculator 15 of the average voltage value of the first half-cycle.

The resulting signal of the calculator 14 of the effective voltage value of the first half-cycle is supplied from the output of the calculator 14 to the control input of the first normally closed electronic key 19, translating this key into an open state, and thereby completing the first half-cycle.

The resulting signal of the calculator 15 of the average voltage of the first half-cycle is supplied from the output of the calculator 15 to the input of the storage device 17, where it is stored and stored until the completion of the second half-cycle.

The calculators 14, 15, 16 begin to perform calculations from the moment the signal arriving from the output of the means 10 for detecting the measuring voltage is proportional to the EMF of the magnetization of the transformer magnetic circuit in the first and second half-periods.

The calculators 14, 15, 16 after each completion of the calculations for the corresponding half-cycle are automatically set to the initial state of readiness for the next calculations, for example, by signals from the clock generator 11, or by key control signals 19 and 20, or in another way.

The calculator 14 of the effective voltage value of the first half-cycle contains an integrated reference voltage source, which sets the desired value of the effective value of the voltage generated in the first half-cycle. The calculator 14 also contains a comparator, which upon reaching the equality of the effective voltage value with the reference voltage provides a signal to the control input of the normally closed key 19 to open and complete the formation of the first half-cycle.

The processes of calculating stresses by the average voltage calculator 15 and the current voltage calculator 14 begin and end at the same time.

The calculated average voltage value from the output of the calculator 15 is sent to channel 13, to the signal input of the means for storing the average voltage value - memory 17, where this value is stored and used during the voltage generation process of the second half-cycle.

When the output signals of the second half-cycle from the output of the means 10 for detecting the measuring voltage, which is proportional to the magnetization EMF of the transformer magnetic circuit, are fed to the input of the average voltage calculator 16, the latter starts to perform calculations. From the output of the calculator 16, a voltage proportional to the average voltage value is supplied to the first input of the comparator 18, and a voltage from the output of the storage device 17, which is proportional to the average voltage value generated in the first half-cycle, is supplied to its second input. When the equality of these voltages is achieved, a signal is generated at the output of the comparator 18, which is fed to the control input of a normally closed switch key 20 — a switch to complete the formation of the second half-cycle, and this switch opens. The voltage generation of the second half-cycle is completed.

In the absence of a control signal for opening, the keys 19, 20 are set to the initial closed state. The keys 19, 20 may contain control circuits in the form of RS-flip-flops or other circuits that ensure their open state after the input signals open and maintain this state until the current signal from the clock generator is completed.

When the inverter is operating, the average voltage values of the pulses generated in the first and second half-periods are equal. For each pair of pulses in one period, the parameters of the first pulse exactly correspond to the required value, at which the required effective value is provided. The described calculations and operations can be performed by means of analog or digital technology. In this case, the output voltage is within the specified tolerances. The output voltage may have asymmetrical tolerances with respect to the specified reference voltage if the output transformer has an voltage inequality of the first and second half-periods, which is caused either by the power source and circuit elements, or by a non-linear load.

The proposed solution allows us to simplify the design and improve the overall dimensions of the facility by reducing the number of connections between the half-period formers and the functional unit for converting direct current into alternating current with a bridge switch.

Information sources.

1. RF patent No. 2282934, Voltage inverter with transformer protection against one-sided saturation.

2. RF patent No. 84173, Bridge inverter with protection of the output transformer from one-sided saturation.

3. RF patent No. 2273087, Method of protection against unilateral saturation of a voltage transformer transformer.

Claims (1)

A bridge inverter with protection of the transformer from one-sided saturation, comprising a bridge switch for converting direct voltage to alternating current, having first and second control inputs, used to control the closure and opening of the switching elements of the bridge switch when generating the output voltages of the first and second half-cycles; output transformer, the primary winding of which is connected to the output of the bridge switch; a clock that sets the period of the output voltage with a duration of the generated output pulses equal to half the period, and having first and second outputs with a shift of the output pulses of the second output by half the period relative to the pulses at the first output; the first voltage generating channel of the first half-cycle with the value of the effective voltage value set for it; a second voltage generation channel of the second half-cycle with an average voltage value equal to the average voltage value of the first half-cycle; means for detecting a measuring voltage proportional to the magnetizing EMF of the magnetic circuit of the output transformer in the first and second half-periods, connected by an output to the inputs of the first and second channels of voltage generation of the first and second half-periods, characterized in that the first control input of the bridge switch is connected to the first via a normally closed electronic key clock output; the second control input of the bridge switch through the second normally closed electronic key is connected to the second output of the clock generator; the control input of the first electronic key is connected to the output of the first voltage generating channel of the first half-cycle; the control input of the second electronic key is connected to the output of the second voltage generating channel of the second half-cycle.