TWI383576B - Electronic dynamic brake speed control device - Google Patents

Description

Electronic dynamic brake speed control device

The invention relates to a speed regulating device, in particular to an electronic dynamic brake speed regulating device.

As shown in FIG. 1, a conventional wind turbine system 1 includes a wind turbine unit 11, a three-phase full-wave rectifier circuit 12, a filter capacitor C _P , a DC current converter 13 and a DC-flow AC inverter 14 .

The wind turbine 11 is used to generate a source of electricity using wind power. The three-phase full-wave rectifier circuit 12 is for converting an AC voltage from the wind turbine 11 into a DC voltage output. The filter capacitor C _{P is} connected in parallel to the output of the three-phase full-wave rectifier circuit 12. The DC converter 13 is configured to adjust the DC voltage level outputted by the three-phase full-wave rectifier circuit 12 to a voltage range acceptable to the DC-to-AC inverter 14. The DC-to-AC inverter 14 converts the adjusted DC voltage into an AC voltage output.

However, when the wind speed rises rapidly and the output power of the wind power unit 11 increases, if the AC output of the system 1 does not introduce the same energy into the load or the mains, or the DC output does not utilize the equivalent power to a battery (Fig. When charging is not shown, the energy generated by the wind turbine 11 at this time will be absorbed by the filter capacitor C _P and the voltage v _p across the filter capacitor C _{P will} rise. For example, a wind turbine with a rated voltage of 24 VDC is used. If the wind speed is 12 meters per second and there is no load output, the highest output voltage v _p can be as high as 150 VDC. Therefore, if the energy continues to accumulate, so that the voltage v _p exceeds the withstand voltage of the filter capacitor C _P and the allowable input voltage of the DC converter 13 , the filter capacitor C _P and the circuit are immediately burned, thereby causing equipment failure. Causes inconvenience in repair and maintenance of wind turbines.

In addition, as shown in FIG. 2, for example, a small wind turbine hybrid power supply system 1' with a power of less than 500 watts usually feeds the power generated by weekdays into the mains by a power end network 15, and The power of a battery 16 after it is fully charged is used as an emergency power supply. Therefore, not only can the service life of the battery 16 be delayed, but emergency power consumption at the time of disaster can be provided. However, since the output voltage of a wind turbine 17 via a three-phase full-wave rectifier circuit 18 must match the specifications of the battery 16, the output DC voltage must be boosted to a high voltage and then converted into an alternating current feed to the mains. The disadvantage is that the power conversion efficiency is lowered due to an increase in the pressure difference.

Moreover, if the wind speed during the typhoon exceeds 25 meters per second, the three-phase full-wave rectifier circuit 18 must be forced to be short-circuited in advance to shut down the wind power unit 17, otherwise, the power supply of the battery is stopped and the power of the battery 16 has been When fully charged, the wind turbine 17 must be disintegrated and dropped due to idling stall, posing a danger of use.

Therefore, the object of the present invention is to provide an electronic dynamic brake speed governing device which can reduce the failure rate of equipment and can effectively protect the safety of the generator.

Therefore, the electronic dynamic brake speed regulating device of the present invention is adapted to receive a DC voltage of a three-phase full-wave rectifier circuit, and output another DC voltage to the DC inverter, and the three-phase full-wave rectifier circuit has an output. The DC converter has an input terminal, and the speed control device comprises: a brake unit, an overflow detection circuit and a control and drive circuit.

The brake unit is electrically connected between the output end of the three-phase full-wave rectification circuit and the input end of the DC converter, and is switchable between a cut-off mode and a conduction mode that generates an on-current. The overflow detection circuit is configured to detect whether a DC voltage value output by the three-phase full-wave rectifier circuit is higher than an upper limit voltage value. When the DC voltage value is higher than the upper limit voltage value, the overflow detection circuit activates the control and drive circuit, and the control and drive circuit causes the brake unit to switch from the cutoff mode to the conduction mode, so that the The energy of the DC voltage is lost due to the generation of the on-current, and the control and drive circuit causes the brake unit to switch from the conduction mode to the cut-off mode until the DC voltage value falls below the upper limit voltage value.

The effect of the invention is that the overflow detection circuit detects the DC voltage value outputted by the three-phase full-wave rectifier circuit, and when the DC voltage value is higher than the upper limit voltage value, the overflow detection circuit starts The control and driving circuit, the control and driving circuit causes the braking unit to switch from the off mode to the conducting mode, so that the energy of the DC voltage is lost due to the generation of the on current until the DC voltage is lowered to a low value. Until the upper limit voltage value. When applied to a wind turbine, there is no known that the DC voltage value of the three-phase full-wave rectifier circuit is continuously increased because the wind speed is too high, and exceeds the withstand voltage of the filter capacitor, so that the filter capacitor and the circuit are thus The problem of equipment failure such as burnout occurs, which can effectively protect the safety of the generator.

The foregoing and other technical contents, features, and advantages of the present invention will be described in the following detailed description of a preferred embodiment with reference to the drawings. Clear presentation.

3, the preferred embodiment of the electronic dynamic brake control devices of the present invention is adapted to receive a three-phase full-wave rectification circuit 2 has a DC voltage v _p, and outputs the DC voltage to another DC converter 3, and the three-phase full-wave rectifier circuit 2 has an output end (not shown), the DC converter 3 has an input end (not shown), the speed control device includes: a brake unit 4, a clamp The unit 5, an overflow detecting circuit 6 and a control and driving circuit 7. In the present embodiment, the three-phase full-wave rectifier circuit 2 is for receiving an AC voltage from a wind turbine 2' and converting it into a DC voltage output. The DC converter 3 is used to adjust the DC voltage level output from the three-phase full-wave rectifier circuit 2 to a voltage range acceptable to the AC-AC inverter 3'. The DC-to-AC inverter 3' converts the adjusted DC voltage into an AC voltage output. It should be noted that in the present embodiment, the present invention is applied to a wind power generator (not shown), and the three-phase full-wave rectifier circuit 2 and the wind power unit 2' belong to the wind power generator, but the present invention It can also be applied to other devices and is not limited to this.

The brake unit 4 is electrically connected between the output end of the three-phase full-wave rectifier circuit 2 and the input end of the DC converter 3, and is switchable between a cut-off mode and a conduction mode that generates an on-current. The brake unit 4 includes a filter capacitor C _P , a brake resistor Z _L , a switch S ₁ and a first diode D ₁ electrically connected to the input terminal. The braking resistor Z _L and the switch S ₁ are connected in series with each other and then connected in parallel with the filter capacitor C _P . The first diode D _{1 is} connected in parallel with the braking resistor Z _L . When the brake unit 4 is in the cut-off mode, the switch S ₁ is in an off state; when the brake unit 4 is in the conduction mode, the switch S ₁ is in an on state, and a current flows from the filter capacitor C _P through the The series path of the braking resistor Z _L and the switch S ₁ consumes energy to the braking resistor Z _L , causing the DC voltage v _{p to} drop. In this embodiment, the braking resistor Z _L is a high heat generating resistor wound from a high-impedance conductor.

The clamping unit 5 is electrically connected between the braking unit 4 and the input end of the DC converter 3, and includes a second diode D ₂ , a third diode D ₃ and a clamping capacitor C ₁ . The second diode D ₂ and the clamp capacitor C ₁ are connected in series with each other and then connected in parallel with the filter capacitor C _P . The cathode of the third diode D ₃ is electrically connected to the second diode D _{2 .} between the clamp capacitor C ₁ and the positive electrode of the third diode D ₃ is electrically connected between the braking resistor Z _{L 1} and the switch S.

The overflow detection circuit 6 is configured to detect whether the DC voltage value v _p output by the three-phase full-wave rectifier circuit 2 is higher than an upper limit voltage value.

When the DC voltage value v _{p is} higher than the upper limit voltage value, the overflow detecting circuit 6 activates the control and driving circuit 7, and the control and driving circuit 7 causes the braking unit 4 to switch from the cutoff mode to The conduction mode causes the energy of the DC voltage v _{p to} be lost due to the generation of the on-current, and the control and drive circuit 7 causes the brake unit 4 to self-determine until the DC voltage value v _p falls below the upper limit voltage value. The conduction mode is switched to the cutoff mode. When the DC voltage v _p value is higher than the upper limit voltage value, the control and drive circuit 7 causes the switch S ₁ is turned on. When the DC voltage value v _p falls below the upper limit voltage value, the highest voltage of the switch S ₁ is limited by the clamp capacitor C ₁ .

As shown in FIG. 4, 5, the present invention utilizes a hysteresis control and the fixed duty cycle of fixed frequency is turned on to limit the range of the DC voltage v _p. When the DC voltage value v _{p is} higher than the upper limit voltage value v _TH , the overflow detection circuit 6 outputs a brake command voltage v _b to the control and drive circuit 7 to make the control and the drive circuit 7 The wave width modulation control chip (not shown) outputs a trigger signal v _{gs 1 of the} fixed frequency and the duty-dependent conduction period to the switch S ₁ , thereby triggering the switch S _{1 to be} turned on, and transmitting the energy of the DC voltage v _p The brake resistor Z _{L is} consumed. Since the braking resistance Z _L of the power consumption for wind turbines 2 '2 times the rated power, so that the wind turbines 2' rotation speed must be lowered, and forces the DC voltage drop v _p. When the DC voltage value v _{p is} less than a brake stop voltage value v _TL , the overflow detection circuit 6 turns the brake command voltage v _b to a low potential and causes the control and drive circuit 7 to stop outputting the trigger signal v. _{Gs 1} , the entire brake speed control device will enter the stop state.

FIG. 6 is a circuit operation timing diagram of the present invention. There are five working modes, and the time elapsed from mode one to mode five is just one working cycle of the trigger signal v _{gs 1} .

FIG. 7 is an equivalent circuit diagram of the present invention. The circuit must consider a first line stray inductance L _{k 1} formed between the anode of the first diode D _{1 and} the anode of the filter capacitor C _P . And a second line stray inductance L _{k 2} formed between the negative electrode of the filter capacitor C _P and the switch S ₁ . The brake resistor Z _L is wound from a high-impedance conductor and has an equivalent resistance R _L and an equivalent inductance L _R .

As shown in FIG. 6 and FIG. 8 , the mode of the circuit starts from the switch S ₁ for a period of time, and the current indicated by the broken line is stored in the filter capacitor C _P via the series path of the brake resistor Z _L and the switch S ₁ . The energy, and the DC voltage v _p begins to drop. This voltage loop may be represented as the equation _{v p = v R + v L} , wherein the voltage v _R and v _L, respectively for the voltage across the brake resistor Z _L and the equivalent resistance R _L L _R of the equivalent inductance, and the inductance The cross-pressure v _L can be expressed as v _L = v _P - v _R = L _R . Di _R / dt . The current climb rate of the linearly rising current i _R can be expressed as di _R / dt = ( v _p - v _R ) / L _R . In addition, during this mode, the diodes D ₁ , D _{2 ,} and D ₃ are in a reverse biased state due to the conduction of the switch S ₁ .

As shown in FIG. 6, 9, two circuits mode starts at the instant of switch S ₁ is turned off, then such inductance L _{k 1,} L _{k 2,} and the energy of L _R will through the third diode D ₃ and the the clamp circuit of _a capacitor C to release energy within the clamp capacitor C _1, because of the smaller capacitance of the clamp capacitor C ₁ and close the switch S _1. In addition, the parasitic capacitance of the switch S ₁ starts to charge, and the parasitic capacitance of the first diode D ₁ and the third diode D ₃ is forced to start discharging, so the current climb rate of the current i _R is during this mode. Still rising slightly. At this time, the voltage v _L can be expressed as v _L = v _P + v _{k 1} + v _{k 2} - v _R , and the current climb rate of the current i _R can be expressed as di _R / dt = ( v _P + v _{k 1} + v _{k 2} - v _R ) / L _R . When the clamping capacitor C ₁ absorbs the energy of the inductors L _{k 1} , L _{k 2} and L _R , the voltage across the two ends V _{C 1} rises slightly, and then the parasitic capacitance of the second diode D ₂ begins. Discharge. When the third diode D ₃ completely receives the current of the switch S ₁ , the mode ends.

As shown in FIGS. 6 and 10, in mode 3 of the circuit, when the energy of the stray inductances L _{k 1} and L _{k 2} is released, the freewheeling energy of the equivalent inductance L _R can be regarded as a current source (figure Not shown), and the voltage across the brake resistor Z _L is 0 volts, and the equivalent inductance L _R will pass through the series path of the second diode D ₂ and the third diode D ₃ . The energy is released across the equivalent resistance R _L and releases the residual amount of electricity inside the first diode D ₁ . At this time, the current flowing through the first diode D ₁ gradually rises and distributes the current flowing through the series path of the second diode D ₂ and the third diode D ₃ , and the equivalent inductance L _R can be Expressed as v _L = v _R = L _R . Di _R / dt . At the same time, the clamp capacitor C ₁ also releases the energy absorbed in the mode 2 back to the filter capacitor C _{P through} the series path of the second diode D ₂ and the third diode D ₃ . The capacitor C is the use of the clamp ₁ clamped to the maximum voltage across the switch S _1, which can effectively reduce the pressure switch S ₁ needs specifications. This mode beyond the ends of the clamping of the voltage across the capacitor C ₁ v _{C 1} is equal to the DC voltage v _p.

As shown in FIGS. 6 and 11, before the start of mode four, the first diode D ₁ has gradually distributed the current flowing through the series path of the second diode D ₂ and the third diode D ₃ , thus During this mode, the freewheeling energy of the equivalent inductance L _R is divided equally between two mutually parallel paths and continues to be dissipated through the equivalent resistance R _L . This mode ends when the switch S _{1 is} again triggered to conduct.

As shown in FIGS. 6 and 12, when the switch S _{1 is} again turned on, the stray inductances L _{k 1} and L _{k 2} must receive the energy across the voltage V _p across the filter capacitor C _P , flowing through the The current of the switch S ₁ gradually rises, and the consumption of the freewheeling energy of the equivalent inductance L _R still maintains the operation of the previous mode. When the influence factors of the stray inductances L _{k 1} and L _{k 2} are small, the current flowing through the switch S ₁ has climbed for a period of time, and gradually fully receives the current flowing through the equivalent inductance L _R . At this time, the diodes D ₁ , D ₂ and D ₃ will be turned on and turned off, and ready to return to the mode one state again, and enter the next duty cycle to continuously release the energy input to the filter capacitor C _P .

In summary, the overflow detection circuit 6 detects the DC voltage value v _p output by the three-phase full-wave rectifier circuit 2, when the DC voltage value v _{p is} higher than the upper limit voltage value v _TH , The overflow detection circuit 6 activates the control and drive circuit 7, and the control and drive circuit 7 causes the brake unit 4 to switch from the off mode to the conduction mode, so that the energy of the DC voltage v _p is due to the conduction current. It is generated and lost until the DC voltage value v _{p is} lowered below the upper limit voltage value v _TH , and there is no known DC voltage value v _p outputted by the three-phase full-wave rectifier circuit 2 because the wind speed is too high. rising, and exceeding the withstand voltage of the filter capacitor C _P, so that the filter circuit capacitor C _P and thus problems such as burning of equipment failure occurs, can effectively protect the safety of the generator, it can really achieve the object of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

2‧‧‧Rectifier circuit

2’‧‧‧Wind crew

3‧‧‧DC converter

3'‧‧‧Reflux

4‧‧‧ brake unit

5‧‧‧Clamping unit

6‧‧‧Overflow detection circuit

7‧‧‧Control and drive circuit

C _P ‧‧‧Filter Capacitor

C ₁ ‧‧‧Clamping capacitor

S ₁ ‧‧‧ switch

Z _L ‧‧‧ brake resistor

D ₁ ‧‧‧First Diode

D ₂ ‧‧‧Secondary

D ₃ ‧‧‧third diode

L _{k 1} ‧‧‧First stray inductance

L _{k 2} ‧‧‧Second stray inductance

L _R ‧‧‧ equivalent inductance

R _L ‧‧‧ equivalent resistance

1 is a circuit block diagram of a conventional wind power generator system; FIG. 2 is a system configuration diagram of a conventional hybrid wind power supply system; FIG. 3 is a preferred embodiment of the electronic dynamic brake speed control device of the present invention; A circuit block diagram of the embodiment illustrates the connection state of the brake speed governing device with a three-phase full-wave rectifier circuit, a wind turbine, a DC current converter, and a DC-connected AC inverter; FIG. 4 is a preferred embodiment. FIG. 5 is a diagram showing the relationship between the brake command voltage and the DC voltage in the preferred embodiment; FIG. 5 is a diagram showing the brake command voltage, the DC voltage, and a trigger signal versus time in the preferred embodiment; FIG. 6 is a view of the preferred embodiment. A circuit operation timing diagram illustrating that the preferred embodiment has five modes of operation; Figure 7 is an equivalent circuit diagram of the preferred embodiment; Figure 8 is an equivalent circuit diagram of the preferred embodiment, illustrating the operation of the circuit during mode one; Figure 9 is a first class of the preferred embodiment. FIG. 10 is an equivalent circuit diagram of the preferred embodiment, illustrating an operating state of the circuit during mode three; FIG. 11 is a first-class operation of the preferred embodiment. FIG. The circuit diagram illustrates the operating state of the circuit during mode four; and Figure 12 is an equivalent circuit diagram of the preferred embodiment illustrating the operation of the circuit during mode five.

2. . . Rectifier circuit

2'. . . Wind turbine

3. . . DC converter

3’. . . Reflux

4. . . Brake unit

5. . . Clamping unit

6. . . Overflow detection circuit

7. . . Control and drive circuit

C _P . . . Filter capacitor

C ₁ . . . Clamping capacitor

S ₁ . . . switch

Z _L . . . Brake resistor

D ₁ . . . First diode

D ₂ . . . Second diode

D ₃ . . . Third diode

Claims (4)

An electronic dynamic brake speed regulating device is adapted to receive a DC voltage of a three-phase full-wave rectifier circuit and output another DC voltage to a DC converter, and the three-phase full-wave rectifier circuit has an output end, The DC converter has an input terminal, and the speed control device comprises: a brake unit electrically connected between the output end of the three-phase full-wave rectifier circuit and the input end of the DC converter, and can be in a cut-off mode Switching between the conduction modes that generate the conduction current, the brake unit includes a filter capacitor electrically connected to the input terminal, a brake resistor, a switch, and a first diode. The brake resistor and the switch are connected in series with each other. And then connected in parallel with the filter capacitor, the first diode is connected in parallel with the brake resistor; an overflow detection circuit is configured to detect whether the DC voltage value outputted by the three-phase full-wave rectifier circuit is higher than an upper limit voltage value And a control and driving circuit, when the DC voltage value is higher than the upper limit voltage value, the overflow detecting circuit starts the control and driving circuit, and the control and driving circuit turns the switch on Causing current from the filter capacitor, and consuming energy to the brake resistor via a series path of the brake resistor and the switch, thereby switching the brake unit from the off mode to the conduction mode, so that the energy of the DC voltage is turned on The current is generated and lost until the DC voltage value falls below the upper limit voltage value, and the control and drive circuit causes the brake unit to switch from the conduction mode to the cutoff mode. The electronic dynamic brake speed regulating device according to claim 1, further comprising a clamping unit electrically connected between the braking unit and the input end of the DC converter, the clamping unit comprising a second diode a second diode and a clamp capacitor, the second diode and the clamp capacitor are connected in series with each other and then connected in parallel with the filter capacitor, and the cathode of the third diode is electrically connected to the second Between the diode and the clamp capacitor, the anode of the third diode is electrically connected between the brake resistor and the switch, and the maximum voltage of the switch when the DC voltage value falls below the upper limit voltage value. Will be limited by this clamp capacitor. The electronic dynamic brake speed governing device according to claim 2, wherein when the DC voltage value is higher than the upper limit voltage value, the overflow detecting circuit outputs a brake command voltage to the control and driving circuit. And causing the control circuit and the driving circuit to output a trigger signal of the fixed frequency and the fixed duty conduction period to the switch, and triggering the switch to be turned on, and the energy of the DC voltage is consumed by the braking resistor, when the DC voltage value is less than a brake stop At the voltage value, the overflow detection circuit turns the brake command voltage to a low potential and causes the control and the drive circuit to stop outputting the trigger signal, and the entire brake speed control device enters a stop state. The electronic dynamic brake speed governing device according to claim 2, wherein the braking resistor is a high heat generating resistor wound from a high-impedance conductor.