TWI449458B - Led driving system - Google Patents

Description

Light-emitting diode drive system

The invention relates to the technical field of light-emitting diodes, in particular to a light-emitting diode driving system.

Light Emitting Diode (LED) is a principle that uses electric energy to directly convert into light energy. A voltage is applied to the two terminals of the positive and negative electrodes in the semiconductor. When the current passes, the electrons are combined with the hole, and the remaining energy is Released in the form of light, depending on the material used, the energy level of the photon enables the photon energy to produce light of different wavelengths, while the human eye can receive light of various colors.

1 is a voltage-current characteristic curve of a light-emitting diode. As shown in FIG. 1, when the forward voltage Vf applied to the light-emitting diode is greater than 2.5 volts, the light-emitting diode is turned on, and the forward voltage Vf is less than 0.0 volt. Does not shine. As can be seen from FIG. 1, the forward voltage Vf is preferably 2.5 to 3.5 volts, and the current of the light emitting diode is 20 mA to 30 mA. At the same time, as can be seen from FIG. 1, when the voltage applied to the light-emitting diode is too large, the light-emitting diode is damaged. Therefore, when the light-emitting diode is used, a plurality of light-emitting diodes are often connected in series, so that the forward voltage Vf of each of the light-emitting diodes is between 2.5 and 3.5 volts. Due to the limitation of voltage and current and serial connection of multiple light-emitting diodes, when applied, the applied external voltage needs to be greater than a so-called starting voltage, and the entire series of light-emitting diodes will emit light.

Figure 2 is a schematic illustration of the use of a conventional AC light emitting diode. An AC power source 210, a first group of LEDs 220, and a second group of LEDs 230, and the forward voltage of the first group of LEDs 220 and the second group of LEDs 230 is 90 volts.

When the output AC voltage of the AC power source 210 is equal to or greater than 90 volts, the lighting of the first group of LEDs 220 is started. When the output AC voltage continues to rise and then drops back to 90 volts, the first group of LEDs 220 is turned off. Similarly, when the output AC voltage is equal to or less than -90 volts, the second group of LEDs 230 is started to be turned on. When the output AC voltage continues to drop and then rises again to -90 volts, the second group of LEDs 230 is turned off.

Referring to FIG. 3, there is shown a current waveform diagram of the AC light emitting diode of FIG. 2, wherein the horizontal axis is time, which is displayed in voltage phase, and the vertical axis is current in mA (milliampere). As shown in FIG. 3, at a phase of about 30 degrees, the voltage begins to be greater than 90V, and the first group of LEDs 220 are illuminated. At a phase of about 90 degrees, the voltage reaches a maximum value, and the current flowing through the first group of light-emitting diodes 220 is about 5.2 mA. When the phase is 150 degrees to 210 degrees, the voltage is less than 90V and greater than -90V. At this time, the first group of LEDs 220 and the second group of LEDs 230 are turned off, so the current is 0 mA. At a phase of about 210 degrees, the voltage begins to be less than -90V, and the second set of light emitting diodes 230 are illuminated. At a phase of approximately 270 degrees, the voltage reaches a minimum and the current through the second set of LEDs 230 is approximately -5.2 mA. When the phase is 330 degrees to 360 degrees, the voltage is less than 90V and greater than -90V. At this time, the first group of LEDs 220 and the second group of LEDs 230 are turned off, so the current is 0 mA.

As can be seen from FIG. 3, the first group of LEDs 220 and the second group of LEDs 230 are sometimes turned on and sometimes turned off, which may cause flickering, which may cause discomfort to the human eye, so as shown in FIG. The prior art is not suitable for use in lighting facilities.

Figure 4 is a schematic illustration of another conventional AC light emitting diode used. As shown in FIG. 4, it is composed of an AC power source 210, a group of LEDs 220 and a full bridge rectifier 250. The working principle is that the AC mains is passed through the full bridge rectifier 250, and the positive and negative AC chords are rectified into a waveform having only a positive half cycle, and the waveform is directly used to directly drive the LED 220. However, such a waveform causes a problem that the light-emitting diode 220 is flickering and the utilization rate is low. Wherein, when the input voltage is low, the input voltage is lower than the on-voltage of the LED 220, so the LED 220 is turned off. When the input voltage is high, the input voltage is greater than the turn-on voltage of the light-emitting diode 220, and the light-emitting diode is in a bright state. In general, the LED 220 is extinguished with the input voltage, and as a result, the utilization ratio of the LED is low and flicker is likely to occur. Therefore, there is still room for improvement in the conventional AC LED driving circuit.

The main object of the present invention is to provide a light-emitting diode driving system which improves the utilization ratio of the overall light-emitting diode with a new architecture, and at the same time increases the blinking frequency of the light-emitting diode, making the human eye unable to detect. .

According to a feature of the present invention, the present invention provides a light emitting diode driving system that uses an alternating voltage to drive a light emitting diode. The driving system includes at least a filter circuit, a rectifier circuit, a valley filling circuit, and a Light-emitting diode light-emitting circuit. The filter circuit receives the AC voltage and filters the AC voltage and current to filter out the harmonic components of the AC voltage and current and generate a filtered AC voltage. The rectifier circuit is coupled to the filter circuit, the rectifier circuit having a first output terminal and a second output terminal for rectifying the filtered voltage and current to generate a rectified voltage and current. The valley filling circuit is connected to the rectifier circuit, and the valley filling circuit changes the conduction time of the rectifier circuit to increase the power factor of the rectified voltage and current and the utilization ratio of the LED. The light emitting diode lighting circuit is connected to the valley filling circuit, and the light emitting diode lighting circuit receives the rectified voltage to generate a light source.

FIG. 5 is a circuit diagram of a light emitting diode driving system 500 of the present invention. The LED driving system 500 uses an AC voltage to drive the LED. The driving system 500 includes a filter circuit 510, a rectifying circuit 520, a valley filling circuit 530, a light emitting diode lighting circuit 540, and A control circuit 550.

The filter circuit 510 is connected to an AC power source V _ac to receive an AC voltage and current, and filters the AC voltage and current to filter out the harmonic components of the AC voltage and current, and generate a filtered AC Voltage V _{ac, filtered} .

The filter circuit 510 is composed of a filter inductor Li and a filter capacitor Ci. The first end 503 of the filter inductor Li is connected to the first end 501 of the AC voltage source V _ac , and the second end 504 is connected to the first end 505 of the filter capacitor Ci. The second end 506 of the filter capacitor Ci is connected. To the second end 502 of the AC voltage source V _ac .

The rectifier circuit 520 is coupled to the filter circuit 510. The rectifier circuit 520 has a first output terminal 521 and a second output terminal 522 for rectifying the filtered voltage and current to generate a rectified voltage. The second output 522 is coupled to a low potential.

The rectifier circuit 520 is composed of a first to fourth rectifying diodes D _R1 , D _R2 , D _R3 , and D _R4 . The anode of the first rectifying diode D _R1 is connected to the second end 504 of the filter inductor Li and the first end 505 of the filter capacitor Ci, and the cathode thereof is connected to the first output end 521 . The anode of the second rectifying diode D _R2 is connected to the second end 502 of the AC voltage source V _ac and the second end 506 of the filter capacitor Ci , and the cathode thereof is connected to the first output end 521 . The anode of the third rectifying diode D _R3 is connected to the second output terminal 522 , and the cathode thereof is connected to the anode of the first rectifying diode D _R1 . The anode of the fourth rectifying diode D _R4 is connected to the second output terminal 522 , and the cathode thereof is connected to the anode of the second rectifying diode D _R2 .

The valley filling circuit 530 is connected to the rectifier circuit 520 for changing the on-time of the rectifier circuit 520 to increase the power factor of the rectified voltage and current. The valley filling circuit includes a first capacitor C1, a first diode D1, a second diode D2, a third diode D3, and a second capacitor C2.

The first end 591 of the first capacitor C1 is connected to the first output end 521 of the rectifier circuit 520. The cathode of the first diode D1 is connected to the second end 592 of the first capacitor C1, and the anode thereof is connected to the second output end 522 of the rectifier circuit 520. The cathode of the second diode D2 is connected to the first output end 521 of the rectifier circuit 520.

The anode of the third diode D3 is connected to the anode of the second diode D2, and the anode thereof is connected to the second end 592 of the first capacitor C1 and the cathode of the first diode D1. The first end 593 of the second capacitor C2 is connected to the anode of the third diode D3 and the anode of the second diode D2, and the second end 594 is connected to the second output 522 of the rectifier circuit 520. In this embodiment, the capacitance value of the first capacitor C1 is the same as the capacitance value of the second capacitor C2.

The light emitting diode lighting circuit 540 is connected to the valley filling circuit 530 to receive the rectified voltage to generate a light source. The LED device 540 includes a first LED module D6, a first switch Q1, a second LED module D4, a second switch Q2, and a diode D5.

The first LED module D6 and the first switch Q1 are connected in series, and the first LED module D6 and the first switch Q1 are electrically connected to the first output of the rectifier circuit 520. 521. Between the second output end 522, the first switch Q1 can be controlled to switch between conducting and non-conducting.

The second LED module D4 and the second switch Q2 are connected in series. The second LED module D4 and the second switch Q2 are electrically connected to the first output of the rectifier circuit 520. 521. Between the second output end 522, the second switch Q2 can be controlled to switch between conducting and non-conducting.

The anode of the diode D5 is connected to the connection point of the first LED module D6 and the first switch Q1, and the anode thereof is connected to the second LED module D4 and the second switch Q2. Between the connection points.

The control circuit 550 is connected to the valley filling circuit 530 and the LED light-emitting circuit 540, and controls the LED light-emitting circuit 540 according to the magnitude of the rectified voltage.

Figure 6 is a circuit diagram of a control circuit 550 of the LED driving system of the present invention. The control circuit 550 controls the first switch Q1 and the second switch Q2 to switch between conduction and non-conduction by voltages VC and VB.

The control circuit 550 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first N-type MOSFET, and a first N-type MOSFET. The second N-type MOSFET field effect transistor NMOS2.

The first resistor R1 is composed of resistors R1a and R1b to prevent an excessive voltage from directly crossing the gate and source of the first switch Q1 when the second N-type MOSFET NMOS is turned on. between. One end of the resistor R1a is electrically connected to the first output end 521, and the other end is connected to one end of the resistor R1b and the gate of the first switch Q1, and the voltage VC is used to control whether the first switch Q1 is turned on or off. . The other end of the resistor R1b is connected to the drain of the second N-type MOS field effect transistor NMOS2.

One end of the second resistor R2 is electrically connected to the first output end 521. One end of the third resistor R3 is electrically connected to the second resistor R2, and the other end thereof is electrically connected to the second output end 522.

One end of the fourth resistor R4 is electrically connected to the first output end 521 , and one end of the fifth resistor R5 is electrically connected to the fourth resistor R4 , and the other end thereof is electrically connected to the second output end 522 .

The first N-type MOS field effect transistor NMOS1 has its drain connected to the gate of the second switch Q2 and the gate of the second N-type MOS field effect transistor NMOS2, and is controlled by the voltage VB. The second switch Q2 is turned on or off, the source thereof is connected to the second output terminal 522, and the gate thereof is connected to the connection end of the fourth resistor R4 and the fifth resistor R5.

The second N-type MOS field effect transistor NMOS2 has its drain connected to the resistor R1b, its source connected to the second output terminal 522, and its gate connected to the second voltage limit R2 and the third resistor The connection end of R3 and the drain of the first N-type MOS field effect transistor NMOS1.

Wherein, when the second N-type MOS field effect transistor NMOS2 is turned on, the voltage across the first resistor R1a is sufficient to turn on the first switch Q1, and when the second N-type MOSFET is used When the NMOS 2 is not turned on, the voltage across the first resistor R1 is insufficient, and the first switch Q1 is turned off.

The control circuit 550 causes the second switch Q2 and the second N-type MOSFET to act as a transistor between the first and second reference voltages when the voltage Vo of the first output 521 of the rectifier circuit 520 is between the first and second reference voltages The NMOS 2 is turned on, and the first switch Q1 is turned on, which causes the second LED module D4 and the first LED module D6 to be in a parallel state. Otherwise, the second switch Q2 and the second N-type MOS field effect transistor NMOS2 are not turned on, which may cause the first switch Q1 to be non-conductive.

The first reference voltage is greater than the second reference voltage, the first reference voltage is determined by the resistance values of the second and third resistors R2, R3, and the second switch Q2 and the second N-type MOSFET. The threshold voltage of the transistor NMOS2 is determined by the resistance values of the fourth and fifth resistors R4 and R5 and the threshold voltage of the first N-type MOSFET.

The working principle of the driving system 500 is as follows: when the filtered AC voltage V _{ac, filtered is} less than the filtered AC voltage V _{ac, filtered} 1/2 voltage peak, the rectifying circuit 520 is in a non-conducting state, when the filtering AC When the voltage V _{ac, filtered is} greater than the filtered AC voltage V _{ac, the filtered} 1/2 voltage peak, the rectifier circuit 520 is in an on state.

When the filtered AC voltage V _{ac, filtered} from 0 to the filtered AC voltage V _{ac, filtered} 1/2 voltage peak, the first diode D1 and the second diode D2 are turned on, the third two The pole body D3 is turned off, and the first capacitor C1 and the second capacitor C2 are in parallel to release energy to the LED light-emitting circuit 540. The voltage Vo of the first output end 521 of the rectifier circuit 520 is the first capacitor. C1 and the second capacitor C2 are clamped at 1/2 of the filtered AC voltage V _{ac , the filtered} peak voltage.

At this time, the control circuit 550 controls the first switch Q1 and the second switch Q2 to be turned on, the diode D5 is turned off, and the second LED module D4 and the first LED module D6 are Parallel state.

Because the filtered AC voltage V _ac at this time is less than the filtered AC voltage V _{ac, and the filtered} 1/2 voltage peak, the second LED module D4 and the first LED module D6 are The parallel state is used to reduce the forward conduction voltage of the second LED module D4 and the first LED module D6 to improve the utilization ratio of the overall LED module at this time.

When the filtered AC voltage V _{ac, filtered is} between the filtered AC voltage V _{ac, the filtered} 1/2 voltage peak and the filtered AC voltage V _{ac, the filtered} voltage peak, the first diode D1 and the second diode The body D2 and the third diode D3 are turned off, the first capacitor C1 and the second capacitor C2 stop discharging, and the voltage Vo of the first output end 521 of the rectifier circuit 520 is filtered with the filtered AC voltage V _ac change.

At this time, the control circuit 550 controls the first switch Q1 and the second switch Q2 to be turned off, the diode D5 is turned on, and the second LED module D4 and the first LED module D6 are In-line state.

When the filtered AC voltage V _{ac, filtered} is the voltage peak of the filtered AC voltage V _{ac, filtered} , the first diode D1 and the second diode D2 are turned off, and the third diode D3 is turned on. A capacitor C1 and the second capacitor C2 are in series and are charged by the filtered AC voltage. The voltage Vo of the first output terminal 521 of the rectifier circuit 520 changes with the filtered AC voltage V _ac .

At this time, the control circuit 550 controls the first switch Q1 and the second switch Q2 to be turned off, the diode D5 is turned on, and the second LED module D4 and the first LED module D6 are In-line state.

Since the filtered AC voltage V _{ac, filtered} is equal to the filtered AC voltage V _{ac, the filtered} voltage peak, the second LED module D4 and the first LED module D6 are in series, A high forward voltage is applied to prevent the second LED module D4 and the first LED module D6 from being burned because the voltage Vo of the first output terminal 521 is too high.

FIG. 7 is a schematic diagram showing the voltage Vo and current of the first output terminal 521 of the present invention. As can be seen from FIG. 7, at the circle A and the circle B, since the first capacitor C1 and the second capacitor C2 are discharged, the level and current level of the voltage Vo of the first output terminal 521 can be maintained at a certain value. The second LED module D4 and the first LED module D6 are turned on to generate a light source. In contrast, conventional techniques often tend to cause the light-emitting diode to flicker due to the current approaching 0 amps or the voltage being too low during this period.

In summary, the LED driving system of the present invention utilizes the characteristics of the capacitor and the diode such that when the input voltage is at a low voltage, the capacitor is discharged in parallel to the LED, and the conduction voltage of the LED is maintained. It is also equipped with various rear-end LED driving circuits to improve the utilization of the overall LED. In addition, at the same time, the blinking frequency of the light-emitting diode is increased, making it impossible for the human eye to detect.

When the input AC voltage is low, the first switch Q1 and the second switch Q2 are turned on by the control signal, and the second LED module D4 and the first LED module D6 are turned on in parallel. When the first capacitor C1 and the second capacitor C2 are connected in parallel, the second LED module D4 and the first LED module D6 are discharged and turned on. When the input AC voltage is high, the first switch Q1 and the second switch Q2 are turned off by the control signal. At this time, the second LED module D4 and the first LED module D6 are connected in series. The second light emitting diode module D4 and the first light emitting diode module D6 are powered by the input power source to turn on, thereby improving the utilization ratio of the light emitting diode and increasing the blinking frequency to the human The extent to which the eye is not easily detectable. Through the invention, the second LED module D4 and the first LED module D6 are both in a conducting state, thereby also reducing the influence of the light source flicker on the human eye.

From the above, it can be seen that the present invention is extremely useful in terms of its purpose, means, and efficacy, both of which are different from those of the prior art. It should be noted that the various embodiments described above are merely illustrative for ease of explanation, and the scope of the invention is intended to be limited by the scope of the claims.

210. . . AC power

220. . . First group of light-emitting diodes

230. . . Second group of light-emitting diodes

250. . . Full wave rectifier

500. . . Light-emitting diode drive system

510. . . Filter circuit

520. . . Rectifier circuit

530. . . Valley filling circuit

540. . . Light-emitting diode light-emitting circuit

550. . . Control circuit

Li. . . Filter inductor

Ci. . . Filter capacitor

D _R1 . . . First rectifier diode

D _R2 . . . Second rectifying diode

D _R3 . . . Third rectifying diode

D _R4 . . . Fourth rectifying diode

C1. . . First capacitor

D1. . . First diode

D2. . . Second diode

D3. . . Third diode

C2. . . Second capacitor

D6. . . First light emitting diode module

Q1. . . First switch

D4. . . Second light emitting diode module

Q2. . . Second switch

D5. . . Dipole

501-506, 591-594. . . end

R1. . . First resistance

R2. . . Second resistance

R3. . . Third resistance

R4. . . Fourth resistor

R5. . . Fifth resistor

NMOS1. . . First N-type MOS field effect transistor

NMOS2. . . Second N-type MOS field effect transistor

Fig. 1 is a graph showing voltage and current characteristics of a light-emitting diode.

Figure 2 is a schematic illustration of the use of a conventional AC light emitting diode.

Figure 3 is a schematic diagram of the current mode of Figure 2.

Figure 4 is a schematic illustration of another conventional use of an alternating current LED.

Figure 5 is a circuit diagram of a light emitting diode driving system of the present invention.

Figure 6 is a circuit diagram of a control circuit of the LED driving system of the present invention.

Figure 7 is a schematic diagram showing the simulation of voltage and current at the first output of the present invention.

500. . . Light-emitting diode drive system

510. . . Filter circuit

520. . . Rectifier circuit

530. . . Valley filling circuit

540. . . Light-emitting diode light-emitting circuit

550. . . Control circuit

Li. . . Filter inductor

Ci. . . Filter capacitor

D _R1 . . . First rectifier diode

D _R2 . . . Second rectifying diode

D _R3 . . . Third rectifying diode

D _R4 . . . Fourth rectifying diode

C1. . . First capacitor

D1. . . First diode

D2. . . Second diode

D3. . . Third diode

C2. . . Second capacitor

D6. . . First light emitting diode module

Q1. . . First switch

D4. . . Second light emitting diode module

Q2. . . Second switch

D5. . . Dipole

501-506, 591-594. . . end

Claims (10)

An LED driving system uses an AC power source to drive a light emitting diode. The driving system includes at least: a filter circuit connected to the AC power source for receiving AC voltage and current, and performing the AC voltage and current Filtering to filter out the higher harmonic components of the alternating voltage and current, and generate a filtered alternating voltage; a rectifying circuit is coupled to the filtering circuit, the rectifying circuit having a first output end and a second output end, Rectifying the filtered voltage and current to generate a rectified voltage and current; a valley filling circuit connected to the rectifying circuit, the valley filling circuit changing an on-time of the rectifying circuit to increase the rectified voltage and current power And increasing the utilization ratio of the light emitting diode; a light emitting diode light emitting circuit connected to the valley filling circuit, the light emitting diode light emitting circuit receiving the rectified voltage to generate a light source; and a control circuit connected to the rectifying The circuit and the LED light-emitting circuit control the LED light-emitting circuit according to the magnitude of the rectified voltage; wherein The light emitting diode circuit comprises: a first light diode module and a first switch connected in series, electrically connected between the first and second output ends of the rectifier circuit, wherein the first switch can be controlled to be turned on Switching between switching and non-conduction; a second LED module and a second switch connected in series are electrically connected between the first and second output terminals of the rectifier circuit, and the second switch can be controlled to be turned on Switch between switching to and not conducting; a diode, the anode is connected to the connection point of the first LED module and the first switch, and the anode is connected between the connection point of the second LED module and the second switch; The control circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first N-type MOSFET, and a second N-type gold An oxy-semiconductor field-effect transistor; wherein the first resistor, the second resistor, and the fourth resistor are coupled to the first output, the third resistor, the fifth resistor, and the second N-type MOSFET The source and the source of the first N-type MOSFET are connected to the second output end, and the first resistor is connected to the drain of the second N-type MOSFET, the second N a gate of the MOS field effect transistor and a drain of the first N-type MOS field effect transistor are connected to a connection end of the second resistor and the third resistor, the first N-type MOSFET a gate of the effect transistor is connected to the connection end of the fourth resistor and the fifth resistor, when the second N-type gold oxide half When the body field effect transistor is turned on, the voltage across the first resistor is sufficient to turn on the first switch, and when the second N-type MOS field effect transistor is not turned on, the voltage across the first resistor is insufficient. And the first switch is turned off. The light-emitting diode driving system of claim 1, wherein the valley filling circuit comprises: a first capacitor, one end of which is connected to the first output end of the rectifier circuit; and a first diode; The cathode is connected to the other end of the first capacitor, and the anode thereof is connected to the second output end of the rectifier circuit; a second diode having a cathode connected to the first output end of the rectifier circuit; a third diode having a cathode connected to the anode of the second diode and an anode connected to the other of the first capacitor One end and a negative electrode of the first diode; and a second capacitor connected to the negative electrode of the third diode and the positive electrode of the second diode, and the other end of which is connected to the second of the rectifier circuit Output. The illuminating diode driving system of claim 2, wherein the capacitance of the first capacitor is the same as the capacitance of the second capacitor. The illuminating diode drive system of claim 3, wherein when the filtered AC voltage is less than a 1/2 voltage peak of the filtered AC voltage, the rectifier circuit is in a non-conducting state, and when the filtered AC voltage is greater than When the 1/2 voltage peak of the AC voltage is filtered, the rectifier circuit is in an on state. The illuminating diode driving system of claim 4, wherein the first diode and the second two are when the filtered AC voltage is gradually increased from 0 to a voltage peak of 1/2 of the filtered AC voltage. The pole body is turned on, the third diode is turned off, the first capacitor and the second capacitor are connected to the light emitting circuit in parallel, and the voltage of the first output end of the rectifier circuit is the first capacitor and the second capacitor The clamp is at a peak voltage of 1/2 of the filtered AC voltage. The illuminating diode driving system of claim 5, wherein the control circuit controls the first switch and the second switch to be turned on, The diode is turned off, and the second LED module and the first LED module are in a parallel state. The illuminating diode driving system of claim 6, wherein the first two poles are when the filtered alternating voltage is between a voltage peak of 1/2 of the filtered alternating voltage and a voltage peak of the filtered alternating voltage The body, the second diode, and the third diode are turned off, and the first capacitor and the second capacitor stop discharging, and a voltage of the first output end of the rectifier circuit fluctuates with the filtered AC voltage. The illuminating diode driving system of the seventh aspect, wherein the control circuit controls the first switch and the second switch to be turned off, the diode is turned on, the second illuminating diode module and the The first light emitting diode module is in a series state. The illuminating diode drive system of claim 8, wherein the first diode and the second diode are turned off when the filtered AC voltage is a voltage peak of the filtered AC voltage. The diode is turned on, the first capacitor and the second capacitor are in series and charged, and the voltage of the first output of the rectifier circuit varies with the filtered AC voltage. The illuminating diode driving system of claim 9, wherein the control circuit controls the first switch and the second switch to be turned off, the diode is turned on, the second illuminating diode module and the The first light emitting diode module is in a series state.